Mushroom

Mushrooms are fungi that grow and spread in dark areas.

Obtaining
Mushrooms can be instantly mined with anything.

Natural generation
Mushrooms naturally generate in poorly lit areas (light level of 12 of less), as well as in mushroom island biomes and the Nether.

Witch huts have a flower pot with a mushroom inside.

Huge mushrooms
Mining a huge mushroom block drops up to 2 mushrooms.

Mobs
Shearing a mooshroom drops 5 red mushrooms.

Usage
Mushrooms can be planted and grown on blocks in light levels below 13 and not directly underneath the sky. If planted on mycelium or podzol, they can stay planted in any light level. Both brown and red mushrooms grow at the same rate regardless of light level.

Besides being mined directly, mushrooms are dropped as items if:
 * the block below them falls, is moved, or destroyed;
 * a fluid flows over them;
 * it is above light level 12 and a block updates next to it.

Huge mushrooms
When bone meal is applied to a mushroom, the mushroom has a chance to grow into a huge mushroom, provided that it has enough space and that the light level is dark enough.

Spread
Mushrooms will spread randomly onto nearby blocks when in appropriate conditions. They will spread only if there are fewer than 5 mushrooms of the same type in 9×9×3 area.

Trivia

 * Red mushrooms bear a strong resemblance to Amanita muscaria mushrooms, more commonly known as fly agarics. Consuming them will cause delirium and hallucinogenic effects if their psychoactive properties have not been reduced by parboiling. Similarly, red mushrooms in the Minecraft Survival Test damaged the player when eaten.
 * Brown mushrooms produce a natural light level of 1.