Volvariella bombycina

Volvariella bombycina, commonly known as the silky volvariella, silky sheath, silky rosegill, silver-silk straw mushroom, or tree mushroom, is a species of fungus in the family Pluteaceae. The fruit body (mushroom) begins developing in a thin, egg-like sac. This ruptures and the stem expands quickly, leaving the sac at the base of the stem as a volva. The cap, which can attain a diameter of up to 20 centimetres (8 inches), is white to slightly yellowish and covered with silky hairs. On the underside of the cap are closely spaced gills, free from attachment to the stem, and initially white before turning pink as the spores mature. It is an uncommon but widespread species, having been reported from Eurasia, Australia, North America, and the Caribbean. The mushroom grows singly or in clusters, often appearing in old knotholes and wounds in elms and maples. It is edible and contains compounds with antibacterial properties....read more on Wikipedia.