Responding to the original question...

I wouldn't *do* anything. I would be annoyed at myself for forgetting to get my quarter sheet off the bench. I would be annoyed at the childish bitch who took it, hid it for a day, and then put it back where she found it. But hey, stuff like that is just part of life. You will, from time to time, forget stuff. Sometimes you'll be lucky and get it back. Sometimes you won't. You will, from time to time, have to deal with childish bitches. And some of them will do worse than this relatively minor thing. Get over it.

If I was the person who found your quarter sheet on the bench and knew it was yours, I would have either put it with your stuff or put it in a safe place and left you a note or told you where it was the next time I saw you. If I didn't know whose it was, I would just leave it alone.

Unless you are always leaving your crap laying around. In that case, if I was the BO, we would have to have a little chat.

I reject your reality and substitute my own.
                                       Adam Savage