Some of TSR's old Mail Order Hobby Shop catalogs from when I was a kid.
Being obsessed with D&D pre-Internet and not having too much money to buy product or a local hobby store, those suckers were sure tantalizing. I probably paged through some of them until they just about disintegrated.
Collage Maps, Adventure-writing Process, A City of Cheese - Matt Finch (Frog God Games, Swords & Wizardry, Tome of Adventure Design, Spire of Iron and Crystal, cats and dogs living together) and I had a loooooooooon...
10 hours ago