Though its bitter taste would stop all but the most determined mycophagists anyway, it should be noted that Hypholoma fasciculare may be poisonous; I do not recommend it as an edible. That said, I have some doubts. Contemporary field guides say the mushroom has proven fatal in Europe and Asia--but so do older field guides, and contemporary authors may be simply reiterating the older claims. It is possible that we are in territory similar to that of Hygrocybe conica, where "four deaths in China" are cited by many authors as proof of the mushroom's toxicity--when the four deaths occurred in a pre-industrial country so long ago that one can't be sure the mushrooms were accurately identified, let alone the cause of the poisoning.

The earliest edibility reference to Hypholoma fasciculare in my library is Nina Marshall's The Mushroom Book (1902, 80), where she says the mushroom is "reputed poisonous." Unlike Hygrocybe conica, however, contemporary authors also cite non-fatal North American evidence--like Arora (1986, 383): "in America only gastrointestinal upsets have been reported." Perhaps these cases could simply result from the bitter taste; in 1949, Alexander Smith noted that "there are reports of people eating this species after boiling the caps in water and of suffering no ill effects" (514). Don't get me wrong, however: I would not eat this mushroom, and I don't recommend that you do, either!

A smaller, southern version of Hypholoma fasciculare, which may or may not be a truly distinct species, is discussed in the comments below.

Description:

Ecology: Saprobic; growing in clusters on decaying logs and stumps of hardwoods and conifers; fall and winter, sometimes in spring; widely distributed in North America.

Cap: 2-5 cm; conical to convex at first, becoming broadly convex to flat; smooth; dry; bright sulfur yellow to greenish yellow when fresh, sometimes yellowish orange when young, often with a darker center; the margin sometimes with small partial veil fragments.

Gills: Attached to the stem or pulling away from it; sulfur yellow, becoming olive or greenish yellow, eventually dusted with spores and therefore spotted purplish brown to blackish (see third illustration); close or crowded.

Stem: 5-12 cm long; 3-10 mm thick; more or less equal, or tapering to base, bright yellow to tawny, developing rusty brown stains from the base upwards; bright yellow partial veil present in buttons (see the bottom illustration), soon disappearing or leaving a ring zone near the top.

Flesh: Thin, yellow.

Taste: Bitter.

Spore Print: Purple brown.

Microscopic Features: Spores: 6-8 x 3.5-5 µ; elliptical; smooth.