This section is from the book "Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc.", by George Francis Atkinson. Also available from Amazon: Studies of American Fungi: Mushrooms, Edible, Poisonous, Etc..
The genus Mycena is closely related to Collybia. The plants are usually smaller, many of them being of small size, the cap is usually bell-shaped, rarely umbilicate, but what is a more important character the margin of the cap in the young stage is straight as it is applied against the stem, and not at first incurved as it is in Collybia, when the gills and margin of the pileus lie against the stem. The stem is cartilaginous as in Collybia. and is usually hollow or fistulose. The gills are not decurrent, or only slightly so by a tooth-like process. Some of the species are apt to be confused with certain species of Omphalia in which the gills are but slightly decurrent, but in Omphalia the pileus is umbilicate in such species, while in Mycena it is blunt or umbonate. The spores are white. A large number of the plants grow on leaves and wood, few on the ground. Some of those which grow on leaves might be mistaken for species of Marasmius, but in Marasmius the plants are of a tough consistency, and when dried will revive again if moistened with water.
Some of the plants have distinct odors, as alkaline, or the odor of radishes, and in collecting them notes should be made on all these characters which usually disappear in drying. A few of the plants exude a colored or watery juice when bruised, and should not be confounded with species of Lactarius.
Mycena galericulata Scop. Edible. - M ycena galericulata grows on dead logs, stumps, branches, etc., in woods. It is a very common and very widely distributed species. It occurs from late spring to autumn. The plants are clustered, many growing in a compact group, the hairy bases closely joined and the stems usually ascending. The plants are from 5-12 cm. high, the caps from 1-3 cm. broad, and the slender stems 2-3 mm. in thickness.
The pileus is conic to bell-shaped, sometimes umbonate, striate to near the center, and in color some shade of brown or gray, but variable. The gills are decurrent by a tooth, not crowded, connected by veins over the interspaces, white or flesh colored. The slender stems are firm, hollow, and hairy at the base.