Hello, it's justcool393. I found a good seed with a mushroom biome next to the spawnpoint. It works from (I've only tested these) 1.1 - 12w22a (and probably future updates). It 1.1, you spawn in a plains biome and in 1.2+, you spawn in a jungle biome.
The seed is "i dont care" without the quotes.
Thanks and have a great day,
justcool393