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 Pre-release, you can make them grow by using Bone Meal on normal mushrooms if, and 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.

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 hat has only its top face covered with the brown texture, the others being the pore texture.

Huge Mushroom
How to create giant mushrooms

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, a Crafting Table and Bones, then planting the mushroom, using the crafting table to convert bones to bonemeal, then using the bonemeal on the mushroom.

Trivia

 * In the 1.8 pre-release, planting a Mushroom on any block and growing it with Bone Meal would change the block to dirt. This could be used on Bedrock, making it possible to get to The Void more easily without hacking.