Glowing Mushroom

The glowing mushroom is created when a mushroom ends up on top of some dead grass, or glowing mycelium. Both regular mushrooms and mushroom blocks can be turned into glowing mushrooms. The item can only exist on dead grass or glowing mycelium, or it will break.

How to get
Have some mushrooms on grass or mycelium, and detonate a radioactive explosion nearby so the mushroom is in the fallout zone.