Last part of June, I was in Iowa for my 50th high school reunion. I went to Freedom Rock.
https://www.instagram.com/explore/locat ... edom-rock/
https://www.thefreedomrock.com/
There are 99 other Freedom Rocks in Iowa, other states have at least one.
South of Freedom Rock, just outside of Greenfield is the Iowa Aviation Museum. While small, it's wort the stop. Check to make sure it's open before stopping.
https://flyingmuseum.com/