I'd missed that the USPS released a set of stamps commemorating Ezra Jack Keats' The Snowy Day back in 2017. From the Smithsonian National Postal Museum:
It was the first full-color picture book to have an African American protagonist. Keats received the 1963 Caldecott Medal for his illustrations.
This book was solidly in the regular reading rotation when my kids were little and I remember it fondly from my childhood as well.