At an estate sale Amelia (my friend) and I found rows upon rows of National Geographics. They dated from the 1930s through 1990s. The best part: They were free! So we took lots and lots for collaging. However we only took the 30s and 40s ones because those are pretty uncommon. I've only ever seen the 60s and 70s ones before at estate sales. I took some pictures of the best clothing photos before we started cutting up the magazines.
(Gasp, vintage enthusiasts if you wish. I can't believe I did it either.)