From the USPS press release November 15, 2024:

Evoking the colorful sights of a seasonal walk in the woods, the photographs on five new postcard stamps depict leaves on trees found in the United States. Antonio Alcalá, an art director for USPS, designed the stamps.Additional information will be posted below the line, with the most recent information at the top.

Updated March 10^th:
Here is what the full pane of 20 looks like:You can click on this picture for a larger version.

Updated February 6^th:
There is only first-day postmark for this issue:From the Postal Bulletin:
On March 14, 2025, in Strongsville, OH, the United States Postal Service® will issue the Vibrant Leaves stamps (Non-denominated priced at the Postcard rate), in five designs, in a pressure-sensitive adhesive (PSA) pane of 20 stamps (Item 124100) and a PSA coil of 100 stamps (Item 740900). These stamps will go on sale nationwide March 14, 2025, and must not be sold or canceled before the first-day-of-issue.

Five new postcard stamps showcase photographs of different leaves in various colors. One leaf from each of the following trees is featured on a stamp: aspen, sassafras, oak, maple, and sweetgum. Art director Antonio Alcalá designed the stamps using existing photographs.

No automatic distribution of either format.

How to Order the First-Day-of-Issue Postmark:
Customers have 120 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office® or at The Postal Store® website at usps.com/shop. 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 – Vibrant Leaves Stamps
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 July 14, 2025.

Technical Specifications (Pane of 20):

Issue: Vibrant Leaves Stamps
Item Number: 124100
Denomination & Type of Issue: Postcard Rate Non-denominated,
Mail-use
Format: Pane of 20 (5 designs)
Series: N/A
Issue Date & City: March 14, 2025, Strongsville, OH 44136
Art Director: Antonio Alcalá, Alexandria, VA
Designer: Antonio Alcalá, Alexandria, VA
Existing Photo: Marie-France Bélanger
Existing Photo: Olga Mitryaeva
Existing Photo: Vladimir Pomortsev
Existing Photo: Adobe Stock
Existing Photo: Paulina Wessel
Modeler: Joseph Sheeran
Manufacturing Process: Offset
Printer: Ashton Potter (USA) Ltd. (APU)
Press Type: Muller A76
Stamps per Pane: 20
Print Quantity: 95,000,000
Paper Type: Nonphosphored Type III, Block Tag
Adhesive Type: Pressure-sensitive
Colors: Cyan, Magenta, Yellow, Black, PMS 7628 C, PMS 3517 C, PMS 159 C, PMS 716 C
Stamp Orientation: Vertical
Image Area (w x h): 0.7300 x 0.8400 in. / 18.5420 x 21.3360 mm.
Stamp Size (w x h): 0.8700 x 0.9800 in. / 22.0980 x 24.8920 mm.
Full Pane Size (w x h): 5.3500 x 4.9300 in. / 135.8900 x 125.2220 mm.
Plate Size: 400 stamps per revolution
Plate Number: “P” followed by eight (8) single digits
Marginal Markings:
Front: Plate number in four corners
Back: © 2024 USPS • USPS logo • Two barcodes (124100) • Plate position diagram (10) • Promotional text

Technical Specifications (Coil of 100):

Issue: Vibrant Leaves Stamps
Item Number: 740900
Denomination & Type of Issue: Postcard Rate Non-denominated,
Mail-use
Format: Coil of 100 (5 designs)
Series: N/A
Issue Date & City: March 14, 2025, Strongsville, OH 44136
Art Director: Antonio Alcalá, Alexandria, VA
Designer: Antonio Alcalá, Alexandria, VA
Existing Photo: Marie-France Bélanger
Existing Photo: Olga Mitryaeva
Existing Photo: Vladimir Pomortsev
Existing Photo: Adobe Stock
Existing Photo: Paulina Wessel
Modeler: Joseph Sheeran
Manufacturing Process: Offset
Printer: Ashton Potter (USA) Ltd. (APU)
Press Type: Muller A76
Stamps per Coil: 100
Print Quantity: 300,000,000
Paper Type: Nonphosphored Type III, Block Tag
Adhesive Type: Pressure-sensitive
Colors: Cyan, Magenta, Yellow, Black, PMS 7628 C, PMS 3517 C, PMS 159 C, PMS 716 C
Stamp Orientation: Vertical
Image Area (w x h): 0.7300 x 0.8400 in. / 18.5420 x
21.3360 mm.
Stamp Size (w x h): 0.9000 x 0.9800 in. / 22.8600 x
24.8920 mm.
Plate Size: 720 stamps per revolution
Plate Number: “P” followed by eight (8) single digits
Coil Number Frequency: Plate number every 30th stamp below stamp image

Updated December 16^th:
These stamps will be issued March 14 in Strongsville, Ohio, which is the site and date of the Garfield-Perry Stamp Show.