Huge mushroom

The Huge Mushroom is a naturally occurring structure which was added to the game in Beta version 1.8. Huge mushrooms are composed of several blocks: mushroom stalks and either red or brown colored blocks for the cap. These blocks provide a valid spawn area for hostile mobs, and may be destroyed by hand to yield 0-2 normal mushrooms. The texture for the blocks which make up the cap depends on their position on it; for example, the corner block of the brown variety 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 and the others covered with the pore texture.

In Beta 1.8, The only known way to create huge mushrooms is by using Bone Meal on normal mushrooms, provided the normal mushroom was planted on dirt. In Beta 1.9, huge mushrooms occur naturally in the mushroom biome. A Huge Mushroom will not grow above the height limit/skybox without modifying the game. When growing huge mushrooms indoors, the brown requires at least a 9x9x8 room, and the red a 7x7x6.

History
In a tweet, Notch showed a picture of a 1.7 change-list(back then 1.8 was planned to be 1.7). 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 "Surqic" 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.

If a player wishes to grow either type under ground there must be a hole leading to surface until the [mushroom] has grown into the larger kind or it will not grow.

Farming
Huge mushrooms can be grown by applying bone meal to a small red or brown mushroom, unless a torch is nearby. The sword is the best tool for destroying huge mushrooms. When destroyed, large mushroom caps have a chance of dropping small mushrooms of their color. Each giant mushroom can be expected to drop 8-20 small mushrooms, making this a viable source of food.

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 in Survival mode without hacking, as well as to grief admin structures made out of it.
 * Huge Red Mushrooms can be used to build a basic hut, either by filling in the space between the cap and the ground, or by digging a large enough hole to accommodate a Huge Mushroom so that the cap intersects with the ground (may take multiple attempts).
 * Carrying brown mushrooms and bonemeal gives explorers the ability to quickly assemble platforms out of Huge Brown Mushrooms, which affords a sleeping platform safe from mobs when illuminated (a single torch in the center is sufficient).
 * In the 1.9 pre release, Huge Mushroom blocks can be acquired in Survival Mode if they are mined with the Silk Touch enchantment. Blocks mined in this way can be used in a furnace, burning as long as wooden planks. The spore texture appears on all sides of their blocks, as this is the default data value for the block, similar to how white wool works.
 * Huge Mushroom stalks give off a light level of 2. You can see the light if you go inside a huge red mushroom and block off the gaps.
 * Red and brown mushroom blocks and mushroom stalks are not available in creative mode.