Found objects are the best part of thrifting....you just never know what you're going to find. I have to say that old photos are one of my favorites. Check out this collection that some feller found in a shoebox for $10. Apparently they are "audition poloroids" from the late 60s of girls who auditioned for a go-go club (and by go-go, I mean yo clothes have gots ta go-go if you want this job...ahem).
Image source: argh, finding the link. Sorry Polaroid man!