Possible Native American Tools/Art?

I decided stop and metal detect this small 1acre plot of trees behind a store I go to. Had about an hour before it got dark so for about 45 minutes I heard maybe 3 total sounds, it was awful! I made my way down into a mini valley and a 4 foot wide creek. I got a solid hit but I could locate it. As I was pulling out rocks it hit me that some of the rock's I was moving nature would have a difficult time creating. So for about 10 minutes I grabbed what I could and then left. It's mid Ohio so I was freezing too. After washing off my finds I noticed painting and symbols on most of them. What I thought was only tools and pottery turned out to be art also. Everytime I turned or flipped one a different animal appeared. I'm wondering if anyone knows what I found and who created it. Thanks