Oh I got too many of those now and I don't like guessing what the drawings are because they make an upset face if I get it wrong
I have a few rocks but I try to convince them not to give me the rock if they'll just want to take it again later. Otherwise the school projects kids make are pretty cool the masks or jars or paintings.
My niece used to draw potato people with stick arms, she was girly little girl and her princesses were potato shaped princess drawings