I have a seed for ps3 with SIX PLUS mushroom biomes. The seed is Miners guide. If that's not correct its Miners Guide. There is NO trees on this world. The only 2 biomes are mushroom Biomes and oceans. You start out on a small normal island. There is one mushroom biome visible from spawn. I'm not sure how many mushroom biomes there are. I just know theres more than six.
Mushroom Biome Wonderland for ps3