Mushroom Block

Mushrooms are a solid block.

In survival mode if you have an axe enchanted with silk touch you can get a secret block. The block is mushroom block, if you chop a huge mushroom block you get it. This glitch also allows you to get ice blocks abd grass blocks in survival mode. -- ARTICLE COURTESY OF LIGHTNING COMICS--

Obtaining
Huge mushroom blocks are most quickly broken with an axe. They can only be retrieved with a Silk Touch tool. When broken using a Silk Touch tool, it will drop a variant with the cap texture on all sides, no matter what part of the mushroom is broken.

Huge mushrooms
Mushroom blocks generate as part of huge mushroom structures.

Creative inventory
In Pocket Edition, you can choose from four types mushroom block: a version with only red cap, a version with only brown cap, a version with only stalk, and a version with only pores. In all other editions, the block is not available in Creative.

Fuel
Huge mushroom blocks can be used as fuel, lasting 1.5 smelting operation per block.

Data values
Mushroom blocks use block ID to determine the type and block data to determine the texture positions. They also have block states which may replace block data in the future.