Summary:
Distinguishing features are the hygrophanous, moist to lubricous, reddish-brown to tawny, rusty, or tan cap, more or less adnexed gills, the smooth stem, growth on the ground, and the white to pale cream spore print. Gymnopus dryophilus is parasitized in some geographic areas: it is covered in any part by the jelly or tumor-like tissue of Syzygospora species of fungus (Collybia jelly).

Cap:
1-5cm across, convex with an incurved margin, becoming broadly convex to broadly bell-shaped to flat or sometimes depressed with an uplifted margin; hygrophanous, dark reddish-brown fading to orangish brown (on the margin first) eventually pinkish buff or grayish orange overall; moist and usually lubricous, bald and surface even when young, surface even when old or torn at the margin, occasionally translucent-striate at margin when faded or water-soaked, (Halling) 1-5(7)cm across, broadly convex with incurved margin, becoming flat or with uplifted, often wavy margin when old, sometimes also slightly umbonate; chestnut brown, to reddish brown, yellow-brown, tawny, or ocher when young and moist, but fading to tan, pinkish tan, yellowish tan, or buff as it dries; smooth, (Arora), buttery in appearance when fresh and moist (Trudell)

Flesh:
thin, up to 0.4cm at disc; whitish to watery yellow brown when old, (Halling), thin; white, (Arora), pliant (Smith)

Gills:
adnexed to nearly free, crowded to close, narrow to moderately broad, broadest near stem; whitish to pinkish buff when young, becoming light buff when old; edges straight and entire, often eroded when old, (Halling), crowded, usually notched or adnexed; white to pale yellow, (Arora)

Stem:
1-5(9)cm x 0.2-0.5(0.8)cm, generally equal and straight, sometimes wider at top and base or subclavate [somewhat club-shaped] or abruptly bulbous at base, somewhat pliant to stringy fibrous, stem soon becoming hollow; whitish or colored like gills at top, below that light buff, becoming cap-colored or orange-yellow, typically the base colored more or less as the top of the stem; dry, bald when young, faintly striate and occasionally subsulcate [slightly grooved] when old, sometimes finely whitish-pruinose at base, often with white rhizomorphs, (Halling), 2-8cm x 0.2-0.6cm, "slender, equal or with a swollen base", hollow, rather tough and cartilaginous; pale cream or colored like cap but often paler; smooth, "white mycelium often visible at base or in surrounding humus", (Arora)

Odor:
none to mild (Halling), none to pleasant, of peaches, (Schalkwijk-Barendsen)

Taste:
mild to slightly unpleasant in older fruiting bodies, (Halling)

Microscopic spores:
spores 5-7 x 2-3.5 microns, elliptic, smooth, inamyloid, not dextrinoid, (Arora), spores (4.8)5.6-6.4(7) x 2.8-3.5 microns, elliptic to oboval in face view, lacrymoid [teardrop-shaped] to elliptic in side view, smooth, inamyloid, acyanophilic; basidia 4-spored, 14-18 x 5.6-7 microns, clavate to subclavate, not siderophilic; pleurocystidia absent, cheilocystidia scattered to abundant, often collapsing along gill edge in older fruitbodies, 15.4-49 ┬╡m long, "clavate contorted to diverticulate or irregularly lobed", sometimes furcate [forked]; "cap cuticle a layer of repent, branched hyphae, often bifurcate, not diverticulate or coralloid, not radially arranged", hyphae 4.2-10.5(14) microns in diameter, with scattered, brown encrusting pigment, thin-walled; clamp connections present in all tissues, (Halling)

Spore deposit:
white to pale yellowish white when fresh, pale yellowish when dry, (Halling), white or pale cream (Arora)

Notes:
Smith indicates G. dryophilus for WA, OR, CA, and Redhead lists reports from BC. It is reported from ID by Andrew Parker, pers. comm. Bigelow reported it from MB, NL, NWT (Ft. Smith), and QC. Guzman reported it from Mexico. It is widespread elsewhere in North America, and in Europe. Vilgalys(1) confirm Gymnopus dryophilus sensu stricto (see SIMILAR) from at least AB, CA, MA, MT, NY, VA, VT, and WV.

EDIBILITY

yes but some people are sensitive, only the caps are tender enough, it is a proficient concentrator of mercury, (Arora), yes but probably should not be eaten when attacked by Collybia jelly, (Lincoff(2)), good tasting, but sometimes causes gastrointestinal upset; discard the stems, (Ammirati)

Synonyms and Alternate Names:
Collybia dryophila (Bull.: Fr.) P. Kumm.