Found medical bills in a used office chair I bought

I picked up a second-hand office chair last week. When I took the seat cushion off to clean it, I found a stack of old papers tucked inside the frame. They were someone's medical bills and insurance letters with their full name and address. It feels wrong to just throw them out with my trash, but I also don't really want to track down a stranger. I'm stuck on what the right thing to do here is.