My neighbors and I have developed a custom that every holiday we go out to lunch at Dairy Queen (for those not familiar, it's a soft-serve ice cream chain). So we find plenty of holidays -- even though we generally skip Thanksgiving and Christmas!
January: NY Day, MLK Day
February: Groundhog Day, Valentine's Day, President's Day
March: Ides of March, St. Patrick's Day
April: April Fool's Day, Earth Day
May: Cinco de Mayo, Mothers Day, Memorial Day
June: Fathers Day, Flag Day, Juneteenth
July: 4th of July
August:
September: Labor Day
October: Indigenous People's Day, Halloween
November: Veteran's Day, Black Friday
December: Hannukah
We also try to celebrate one or two Jewish holidays as they occur along the way.
As you can see, there's no famous holiday in August. We'll have to consult this list, and maybe pick Woman Astronomers Day or National Coloring Book Day or Big Forehead Day.
https://nationaltoday.com/august-holidays/