Updated October 2nd: Here are the Scott catalogue numbers:

UX647 (34¢) Azulillo postal card
UY54 (34¢+34¢) Azulillo paid reply postal card

Updated July 7th:
On August 11, 2017, in Independence, OH, the U.S. Postal Service® will issue the Azulillo stamped card Forever® priced at 38 cents (34-cent postage + 4-cent surcharge) in one design.

The U.S. Postal Service issues the Azulillo stamped card for 2017 featuring an illustration of a Chilean blue crocus (Tecophilaea cyanocrocus) from pre-existing artwork by famed illustrator and designer Dugald Stermer (1936-2011). His penciled calligraphy under the flower indicates one of its common names, azulillo, which loosely translated from Spanish means “little blue thing,” with its botanical name above. Art director Ethel Kessler designed the stamped card.

The Azulillo stamped card will be available in the following formats:

• Single-cut cards (Item 250000)
• Double-reply cards (Item 250400)
• Sheet of 40 cards (Item 250500)

Stamp Fulfillment Services 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. They may purchase new stamps at their local Post Office, at The Postal Store® website at usps.com/shop, or by calling 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 – Azulillo Stamped Card
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 October 11, 2017.

Philatelic products for the stamped cards are as follows:
Single-cut

• 250016 First-Day Cover, $0.50

Double-reply

• 250416 First-Day Cover, $0.88

Technical Specifications:

Issue: Azulillo Stamped Card
Item Number: 250000
Denomination & Type of Issue: Forever Stamped Card Rate
Format: Single-cut Card
Series: N/A
Issue Date & City: August 11, 2017, Independence, OH 44131
Art Director: Ethel Kessler, Bethesda, MD
Designer: Ethel Kessler, Bethesda, MD
Typographer: Ethel Kessler, Bethesda, MD
Existing Art: Dugald Stermer
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Heidelberg, Speedmaster
Print Quantity: 3,840,000 stamped cards

Technical Specifications:

Issue: Azulillo Stamped Card
Item Number: 250400
Denomination & Type of Issue: Forever Stamped Card Rate
Format: Double-reply Card
Series: N/A
Issue Date & City: August 11, 2017, Independence, OH 44131
Art Director: Ethel Kessler, Bethesda, MD
Designer: Ethel Kessler, Bethesda, MD
Typographer: Ethel Kessler, Bethesda, MD
Existing Art: Dugald Stermer
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Muller A76
Print Quantity: 288,000 double-cut cards
Paper Type: Nonphosphored Type III, Block Tag applied
Adhesive Type: N/A
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Black, Cyan, Magenta, Yellow
Image Orientation: Horizontal
Card Size (w x h): 5.5 x 7.0 in/139.70 x 177.80 mm
Plate Size: 12 cards per revolution
Plate Numbers: N/A
Marginal Markings: ©2016 USPS • Recycling Logo
Paper Type: Nonphosphored Type III, Block Tag applied
Adhesive Type: N/A
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Black, Cyan, Magenta, Yellow
Image Orientation: Horizontal
Card Size (w x h): 5.5 x 3.5 in/139.70 x 88.90 mm
Plate Size: 40 cards per revolution
Plate Numbers: N/A
Marginal Markings: ©2016 USPS • Recycling Logo

Technical Specifications:

Issue: Azulillo Stamped Card
Item Number: 250500
Denomination & Type of Issue: Forever Stamped Card Rate
Format: Sheet of 40 Cards
Series: N/A
Issue Date & City: August 11, 2017, Independence, OH 44131
Art Director: Ethel Kessler, Bethesda, MD
Designer: Ethel Kessler, Bethesda, MD
Typographer: Ethel Kessler, Bethesda, MD
Existing Art: Dugald Stermer
Modeler: Joseph Sheeran
Manufacturing Process: Offset, Microprint
Printer: Ashton Potter (USA) Ltd. (APU)
Printed at: Williamsville, NY
Press Type: Heidelberg, Speedmaster
Print Quantity: 4,000 sheets of 40 cards
Paper Type: Nonphosphored Type III, Block Tag applied
Adhesive Type: N/A
Processed at: Ashton Potter (USA) Ltd. (APU)
Colors: Black, Cyan, Magenta, Yellow
Image Orientation: Horizontal
Card Size (w x h): 5.5 x 3.5 in/139.70 x 88.90 mm
Plate Size: 40 cards per revolution
Plate Numbers: N/A
Marginal Markings: ©2016 USPS • Recycling Logo

Updated July 6th: There is a pictorial B&W first-day postmark for this issue: It measures 2.9″ x 1.12″. In addition, there will also be a show pictorial for Americover.

Updated March 13th: The USPS says this stamped card will be issued August 11 in Independence, Ohio. That would coincide with the first day of Americover 2017, the annual show and convention of the American First Day Cover Society.

from the USPS December 28, 2016:

The U.S. Postal Service issues a new stamped card for 2017 featuring an illustration of a Chilean blue crocus (Tecophilaea cyanocrocus) from pre-existing artwork by illustrator and designer Dugald Stermer (1936–2011). His penciled calligraphy under the flower indicates one of its common names azulillo — loosely translated from Spanish, it means “little blue thing”— with its botanical name above. The Chilean blue crocus is hardy in U.S. Department of Agriculture zones seven to nine. It generally flowers in February or March in North America. Art director Ethel Kessler designed the stamped card.