Here's some cool finds over the years. The round stones vary from about 2"s to 5"s in diameter.Also some choppers,mano's etc...I like the tools alot as well!
I dont see "game balls" in Dr H's book but at a minimum kids will be kids...any objects that round would have been a least a passing interest for a kid.
I dont have a pic but the extensive museum displays at the Cahokia mounds of artifacts of all types excavated from mound areas had quite a few of them and labeled " game balls"....