Last weekend I found my people, and they are the Kaw Valley Seeds Project.
Basically, it's a seed bank whose purpose is to keep alive varieties of plants (through seeds) that are especially adapted to our area. I had no idea this group existed until I saw an advertisement for their annual seed fair, which was last Saturday.
Although, ideally, I would have had my own saved seeds to trade (and next year I certainly will), the goal is to get seeds out into the community, so it was cool to just take seeds too. And--although I limited myself to things I already had on my "to-grow" list--I was kid-in-a-candy-store excited!
Unless you're looking for something really, really rare, the internet has essentially ended any problems finding odd seeds. But you still have to get them delivered and you still don't know how they'll do in your particular climate with your particular bugs. In addition to some common seeds--cilantro, habanero peppers, moon and stars watermelon--I was able to find both green cotton and luffa gourds, two things I was just sure I was going to have to special order.
And--now I'm gushing, I'm sorry--the history! The cotton? Originally found "in with a squash" in 1982, somewhere in Missouri. The habanero's? The gardener who offered them's favorite, as they apparently reliably turn orange like they're supposed to (a difficulty I've had with peppers). You can't buy bits like that!