Minecraft/Mushroom Island Hunt

Mushroom islands are an incredibly rare biome that spawn no mobs except for mooshrooms. They are the only natural place to have mycelineum (dirt variant that helps mushrooms grow) and have many mushrooms.

Mushroom Island Finding
Mushroom islands are incredibly rare, and, as the name implies, are typically islands. Sailing around in a boat with a map is the easiest way to find one using only in-game methods.

Mooshroom Milking
Mooshrooms only spawn on mushroom islands, and, in addition to being milkable with a bucket like cows, can also be "milked" with a bowl for infinite mushroom stew.