Here's Atlas Obscura's list of the largest roadside attractions in the midwest. There's nothing like a greatly oversized item to add some excitement and silly photos to a road trip adventure. You can visit this gigantic horseshoe crab in Ohio. You can even go inside of it and do whatever one does when inside of a massive horseshoe crab (Just be respectful of the owner's property if you decide to visit).
If you're in Wisconsin, you can put a coin inside of this giant cow sculpture, which is said to be the largest talking cow sculpture in the world. Her name is Chatty Belle and she looks friendly, but with a suspicious look in her eyes. In Iowa lies the world's tallest concrete gnome. His name is Elwood and he resides at the Verdant Reiman Gardens at Iowa State University.
There are 22 places on this whimsical list, and I would be happy to visit any of them if I get the chance.