My oldest: 2nd printing of GDW's Traveller in _mint_ condition. Found it in the original shrink wrap (mostly, though some had come off) many (10?) years back. The box has been openned twice: once for me to see what I'd just bought; once to check the copyright date (1981) just a few minutes ago. I really ought to stick this puppy on eBay.
My best "old school" story (I've been playing since I was about 10, so that'll help the dates make sense):
Back in about 1993-94, when I was in college, I was part of a team scavenger hunt. I was showering or something when the list arrived, and when I came into the room, my team said, "we've got ideas for most of the items, but one of the really big point items is hopeless. They want us to find a 'complete set of 1st Edition AD&D hardcovers.'"
I said, "No problem, they're in my dorm room" (down the hall).