Witches are always associated with Halloween, so this next seed is a logical fit. Enter the seed code or number, and you'll spawn near a witch hut in a swampy biome, on the edge of a plain, and with a taiga biome in the distance.
This isn't an empty hut either. The witch is in, and she's waiting for you, so you'll want to be combat-ready. The landscape itself is rather eerie, but the hut also serves as a nice way to get some witch farming started, if you want to reap the resource benefits of it, with drops including things like gunpower and redstone dust.