Armillaria mellea

Armillaria mellea, commonly known as honey fungus, is an edible basidiomycete fungus in the genus Armillaria. It is a plant pathogen and part of a cryptic species complex of closely related and morphologically similar species. It causes Armillaria root rot in many plant species and produces mushrooms around the base of trees it has infected. The symptoms of infection appear in the crowns of infected trees as discoloured foliage, reduced growth, dieback of the branches and death. The mycelium is capable of producing light via bioluminescence. The mushroom is widely distributed in temperate regions of the Northern Hemisphere, usually in heavy soils with temperatures under 79 F (26 C). It typically grows on hardwoods but may be found around and on living and dead wood or in open areas.

from Wikipedia