The Scott catalogue number for this issue is 5256.
From the USPS; further updates will appear after the initial, introductory entry:
Meyer Lemons 
Meyer Lemons is a 2-cent definitive stamp. The stamp art features a whole Meyer lemon next to two wedges of the cut fruit.
This stamp will be issued January 19th in Kenner, Louisiana. That coincides with the Winter Stamp Fest & Postcard Show.
Updated December 21st from the Postal Bulletin:
On January 19, 2018, in Kenner, LA, the U.S. Postal Service® will issue the 2-cent denominated Meyer Lemons stamp, in one design, in a pressure-sensitive adhesive (PSA) coil of 10,000 stamps (Item 760400). The stamp will go on sale nationwide January 19, 2018.
The Meyer Lemons stamp is a new 2-cent definitive stamp that features a whole Meyer lemon next to two wedges of the cut fruit. The illustrations were created with pen and ink and watercolor. Art director Derry Noyes designed the stamp with an existing illustration by John Burgoyne.
Availability to Post Offices: Item 760400, 2-cent Meyer Lemons PSA Coil of 10,000 Stamps
Stamp Fulfillment Services (SFS) will not make an automatic push distribution to Post Offices™.
How to Order the First-Day-of-Issue Postmark:
Customers have 60 days to obtain the first-day-of-issue postmark by mail. Each cover must have sufficient postage to meet First-Class Mail® requirements. They may purchase new stamps at their local Post Office, at The Postal Store® website at usps.com/shop, or by phone at 800-782-6724. They must affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:
FDOI – Meyer Lemons Stamp
USPS Stamp Fulfillment Services
8300 NE Underground Drive, Suite 300
Kansas City, MO 64144-9900
After applying the first-day-of-issue postmark, the Postal Service will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. There is a 5-cent charge for each additional postmark over 50. All orders must be postmarked by March 19, 2018.
Technical details for the Meyer Lemons stamp will appear in a future edition of the Postal Bulletin.
Updated December 27th: Here is the pictorial first-day postmark: 
It measures 2.03” x 1.5”.
Updated January 5th, from the Postal Bulletin:
Philatelic products for this stamp issue are as follows:
-
- 760416 First-Day Cover, $0.95.
- 760415 coil strips of 500, $10.00 [added February 1]
Technical Specifications:
Issue: Meyer Lemons Stamp
Item Number: 760400
Denomination & Type of Issue: 2-cent Denominated, Mail-use
Format: Coil of 10,000 (1 design)
Series: N/A
Issue Date & City: January 19, 2018, Kenner, LA 70062
Art Director: Derry Noyes, Washington, DC
Designer: Derry Noyes, Washington, DC
Typographer: Derry Noyes, Washington, DC
Existing Photos: John Burgoyne, West Barnstable, MA
Modeler: Sandra Lane/Michelle Finn
Manufacturing Process: Offset, Microprint
Printer: Banknote Corporation of America
Printed at: Browns Summit, NC
Press Type: Alprinta 74
Stamps per Coil: 10,000
Print Quantity: 100,000,000 stamps
Paper Type: Nonphosphored Type III
Adhesive Type: Pressure-sensitive
Processed at: Banknote Corporation of America, Browns Summit, NC
Colors: Pantone 7413, Cyan, Magenta, Yellow, Black
Stamp Orientation: Vertical
Image Area (w x h): 0.73 x 0.84 in./18.54 x 21.34 mm
Stamp Size (w x h): 0.87 x 0.98 in./22.10 x 24.89 mm
Plate Size: 560 stamps per revolution
Plate Numbers: “B” followed by five (5) single digits
Coil Number Frequency: Plate numbers every 28th stamp below stamp image
Added February 1:
Collectors can order coil strips of 500 from Stamp Fulfillment Services (USPS.com or 800-STAMP-24). The order number is 760415.
Added January 17, 2019:
A 3,000-stamp coil was added, effective January 27th. It is item 750000.
With this Priority Mail Express stamp, the Postal Service celebrates the Sleeping Bear Dunes, a national park in Michigan that takes its name from a Native American legend.
With this new Priority Mail Express stamp, the U.S. Postal Service celebrates the Sleeping Bear Dunes, which take their name from a Native American legend. Rising 450 feet above Lake Michigan, the dunes are the highest perched dunes in the Great Lakes region and are protected within Sleeping Bear Dunes National Lakeshore. The stamp art celebrates the grandeur and serene natural beauty of the dunes and surrounding park. Dune grasses mark the beach in the foreground, as gulls dive and soar in the breeze. Art director Greg Breeding designed the stamp with original art by Dan Cosgrove.
It measures 2.62” x 1.47” 
It measures 2.98” x 1.35”
This Priority Mail stamp features a colorful illustration of the Byodo-In Temple, a popular tourist attraction in Hawai‘i.
This Priority Mail stamp features a colorful illustration of the Byodo-In Temple, a popular tourist attraction in Hawaii. A smaller-scale concrete replica of a wooden Buddhist temple in Japan, the Byodo-In Temple is located in a private cemetery on the island of O‘ahu. Built in 1968 to commemorate the centennial of the first Japanese immigration to Hawaii, the temple is used for ceremonies, services, and events such as classes and concerts. Art director Greg Breeding designed this stamp with original art by Dan Cosgrove.
The Digital Color Postmark measures 2.78” x 1.72” 
The pictorial postmark measures 2.95” x 1.46”
5301 (50¢) Art of Magic – Rabbit in Hat
The Postal Service celebrates the art of magic with this pane of 20 stamps featuring digital illustrations of five classic tricks magicians use to amaze and delight audiences: a rabbit in a hat (production), a fortune teller using a crystal ball (prediction), a woman floating in the air (levitation), an empty bird cage (vanishing), and a bird emerging from a flower (transformation).
purchase new stamps at their local Post Office or at The Postal Store website at 
Stamps per Pane: 20
All five DCPs measure 2.29″ x 1.06″. The B&W pictorial is 2.99″ x .99″.
Updated August 2nd, from the Postal Bulletin:
What:
Original announcement:
The newest stamp in the Music Icons series honors singer and songwriter John Lennon (1940–1980), a rock ’n’ roll hero successful both as a founding member of the Beatles and as a solo artist.
It measures 2.97″ x 1.50″. Here is the B&W pictorial postmark:
It measures 2.99″ x 1.28″. Here is the special postmark for use by other post offices than the first-day city: 
It measures 2.93″ x 1.46″.
Updated May 10th: 
It measures 1.75″ x 1.37″. Here is the B&W pictorial postmark:
It measures 2.87″ x 1.46″.
The Postal Service celebrates dragons, the high-flying, fire-breathing mythological creatures that have roamed our imaginations for millennia.
WASHINGTON — The U.S. Postal Service will be joined by the American Philatelic Society (APS) to unveil four colorful stamp designs of 16 Forever stamps depicting dragons — the high-flying, fire-breathing mythological creatures that have roamed our imaginations for millennia — at the APS national summer convention and stamp show Aug. 9-12 in Columbus, OH.
English, APS executive director. “There will be something for the whole family highlighting this cool theme. No experience necessary, so we hope you join us!”
folk religion and ancient lore. The Chinese, in particular, have venerated the dragon for thousands of years.
5307 (50¢) Dragons – Green Dragon and Castle
With this stamp, the Postal Service pays tribute to the sacrifice of American soldiers and millions of supporters on the home front who experienced World War I. Entering World War I (1914–1918) in its later stages, the United States helped turn the tide of war in favor of the Allies.
On July 27, 2018, in Kansas City, MO, the U.S. Postal Service® will issue the World War I: Turning the Tide stamp (Forever® priced at the First-Class Mail® rate) in one design, in a pressure-sensitive adhesive pane of 20 stamps (Item 477400). The stamp will go on sale nationwide July 27, 2018.
On July 4, 2018, in Colorado Springs, CO, the U.S. Postal Service will issue the O Beautiful stamps (Forever priced at the First-Class Mail rate) in 20 designs, in a pressure-sensitive adhesive pane of 20 stamps (Item 565300). The stamps will go on sale nationwide July 4, 2018.
Availability to Post Offices: Item 565300, O Beautiful (Forever Priced at the First-Class Mail Rate) Commemorative Pane of 20 Stamps: Stamp Fulfillment Services will make an automatic push distribution to Post Offices of a quantity to cover approximately 30 days of sales.
Issue: O Beautiful Stamps
Colors: Black, Cyan, Magenta, Yellow, PMS Cool Gray 7
What:
The Digital Color Postmark measures 2.71″ x 1.16″. 
The Black & White pictorial measures 2.75″ x 1.10″.
FDOI – Frozen Treats Stamps
Typographer: Leslie Badani, Alexandria, VA
The first-day-of-issue dedication ceremony, free and open to the public, will take place at 6 p.m. CDT at Austin’s 
This booklet of 20 stamps showcases the work of Margaret Berg of Santa Monica, CA, depicting whimsical watercolor illustrations of frozen treats. Each of the 10 stamp designs includes two different treats. The words “FOREVER” and “USA” appear along the bottom of each stamp.
Stamp ideas welcome
Background: 
The Digital Color Postmark measures 2.48 x 1.45 inches.
The Black-and-White pictorial measures 2.80 x 1.16 inches.
