Rhodocollybia butyracea, commonly known as the buttery collybia, is a species of fungus in the family Omphalotaceae. It has a number of subspecies.
The cap is across. It is convex and becomes broadly convex or almost flat. When fresh, this species is smooth and moist. It has a reddish-brown colour fading to cinnamon.
The gills are either free from the stem, or narrowly attached. They range from close to crowded and are whitish. Occasionally, they develop a pinkish tone as they age, and often form fine, jagged edges.
The stem is up to 10 cm long and 1 cm thick. It is normally somewhat club-shaped. It can either be moist or dry.
The flesh of this species is white. There is no distinctive odor or taste.
The spores are pale yellowish, pale pinkish, or white.
It can resemble R. badiialba, R. prolixa, and Gymnopus dryophilus.
Rhodocollybia butyracea is widely distributed in North America.
This species is saprobic. It decomposes litter from conifers, usually that of the genus Pinus, and occasionally hardwoods.
This mushroom is edible, but unsubstantial, and can resemble inedible species.