These are subject to approval by the US Postal Service and will be available at Great American Stamp Show 2024. The first two may be used on first day covers for Pinback Buttons and Autumn Colors, respectively.
Americover was the independent show and FDC celebration of the American First Day Cover Society from 1993 through 2019. It was slated to become part of Great American Stamp Show in 2020, but that was pushed back by a year because of the COVID-19 pandemic.
Updated July 16th:
Due to concerns about copyrights, the Sunday postmark has been revised: 
I’m going to use Sunday’s postmark to commemorate Willie Mays.