Brown Mushroom is a vanilla fungus that emits light level 1 and grows into a flat parasol-shaped huge mushroom.
Guide
Search dark caves with light level 12 or below, the Nether, or any Mushroom Fields biome where they grow at any light level.
Place Brown Mushrooms on podzol or mycelium under light 12 or lower; they spread slowly within a 4-block radius if nearby mushroom count is low.
Plant a Brown Mushroom on dirt, podzol, or mycelium with low light and use bone meal — a wide flat parasol cap forms when there is open vertical space.
Combine 1 Sugar + 1 Brown Mushroom + 1 Spider Eye to brew Potions of Weakness, Slowness, Invisibility, and Harming.
Place 1 Red Mushroom, 1 Brown Mushroom, and 1 Bowl in the crafting grid to get a Mushroom Stew that restores 6 hunger.
Yes. Brown Mushroom emits light level 1 — small but the only passive light from a small Minecraft plant; Red Mushroom emits 0.
No. The Fermented Spider Eye recipe (Sugar + Brown Mushroom + Spider Eye) accepts only Brown Mushroom.
Plant on dirt, podzol, or mycelium at light 12 or below with vertical clearance, then apply bone meal — it forms a flat parasol-shaped huge mushroom.
Lightning striking a Red Mooshroom converts it into a Brown Mooshroom; shearing one drops a Brown Mushroom and turns it into a regular cow.
It has a 65% chance to raise the composter level per item.