Huge mushroom

The Huge Mushroom is a naturally occurring structure which was added to the game in Beta version 1.8. Huge mushrooms can be destroyed to drop more regular mushrooms of the same type. They will be composed of several blocks: mushroom stalks and either red or brown colored blocks for the head. You cannot grow a Huge Mushroom above the height limit/skybox without modifying the game.

In Beta 1.8, you can make them grow by using Bone Meal on normal mushrooms only if the mushroom was planted on dirt (However, mushrooms may be planted on sand, but once bone meal is used on them, a dirt block will appear under the mushroom). It is currently unknown if normal mushrooms can become huge mushroom another way. Both the blocks making the stalk and the head of huge mushrooms can be quickly destroyed by hands and drop 0-2 small mushrooms.

When growing huge mushrooms indoors, the brown requires at least a 9x9x8 room and the red a 7x7x8.

Interestingly enough, the texture of huge mushrooms' caps depends on their position on it. For example, the corner block of a giant brown mushroom hat has 3 sides with the brown texture and 3 sides with the pore texture, while a block in the middle of the cap has only its top face covered with the brown texture, the others being the pore texture.

History
In a tweet, Notch showed a picture of a 1.8 change-list. Although it was completely blurred out and was, at first, thought of as a joke, but then Notch stated that one of the pictures with the new lighting system and the change list had a secret in them. People all around the web started speculating.

One place that people discussed it was on the Minecraft forums, where it was discovered that the tabs at the top of the change list, which were partly covered, could be decoded based on the one pixel tall pattern available in the image.

After a user named "tmcaffeine" successfully decoded, the tabs read: ExperienceOrb.java, changelist.txt, Level.java, Tile.java, HugeMushroomTile.jav(a?), HugeMushroomFeature.(java?), RandomLevelSource(cut) that led people to speculate that huge mushrooms will be added, and indeed, later on Notch revealed a screen shot on Google+ in which two huge mushrooms can be seen as well as an NPC Village.

In the 1.8 pre-release, huge mushrooms did not generate naturally, but could be planted by the player by using Bone Meal on a red or brown Mushroom. In the pre-release version 1 of 1.8's Creative Mode, since the blocks composing a huge mushroom and bonemeal were not included in the item selection menu, the only way to create huge mushrooms is to give yourself regular Mushrooms and Bonemeal, then planting the mushroom, then using the bonemeal on the mushroom.

Farming
Huge mushrooms can be grown using bonemeal and then destroyed to drop more small mushrooms. It is possible to continue to grow and destroy the mushrooms for produce, so long as enough bonemeal is available. As each giant mushroom can be expected to drop two dozen or more small mushrooms, two bonemeal can be used to generate potentially a hundred or more points of hunger bar, making them something of a miracle crop.

Huge mushrooms are destroyed faster wielding a sword.

Uses as a house
Huge Red Mushrooms can be used as a small hidden room on the condition that the cap starts at least 1 block from the ground. by placing ladders on the 3 stalk blocks nearest the floor, removing the rest of the stalk and then placing half blocks around the inside of the cap except above the ladder.

Huge Red mushrooms can also be made in to a basic room once the stalk is removed. The mushroom will not touch the ground however, leaving a gap. Fill this gap with dirt or other material and add doors or windows. An alternate way to do this is to dig a square down in dirt and put the Red Mushroom inside. Then, use bonemeal on the mushroom, and it should touch the ground. Then, just remove the stalk, replace the dirt you removed, and add doors and windows.

Occasionaly the "walls" of the mushroom will be one block off the floor if using this technique and will allow spiders and other smaller mobs to get in because the height of a giant mushroom can vary and is not always the same.

Trivia

 * Planting a Mushroom on any block and growing it with Bone Meal changes the block to dirt. In Beta 1.8 pre1, mushrooms did not have to be on dirt or grass to be able to grow, so this could be used on Bedrock, making a quick and easy way to get to The Void without hacking.
 * While in Survival huge mushroom blocks cannot be acquired, it is possible to manipulate the blocks from huge mushrooms with pistons.
 * If you hack in huge mushroom blocks into the game they can be used in a furnace, burning as long as wooden planks.