E-Flora BC: Electronic Atlas of the Flora of British Columbia

Summary:
Features include a hygrophanous reddish-brown cap, thin flesh, crowded narrow gills, a tough stem darker or lighter than cap, usually with whitish fine hairs, and growth on ground, often in clusters. Gymnopus confluens was moved in 2019 to Marasmiellus but there are problems with the placement and it is likely not to be permanent. Marasmiellus confluens is quite common in the Pacific Northwest under conifers - in eastern North America it favors hardwoods, (Arora).

It has been found at least in BC (collections at the Pacific Forestry Center and the University of British Columbia), WA (collections at the University of Washington), more widely in North America (including according to Lincoff(2) QC, NC, CA, CO), and Europe, North Africa, and Asia (Breitenbach(3)). It is reported (in Guzman(2)) from Mexico.

Gills:
"adnate to adnexed or nearly free", sometimes forming a slight collar round top of stem, crowded to close, narrow, 0.05-0.1cm, thin; pinkish buff to pinkish cinnamon at first, becoming cream colored when old; edges even to fimbriate [fringed] to minutely pubescent, (Halling), "adnate soon becoming adnexed or even free", crowded, narrow; whitish to flesh-colored, (Arora)

Stem:
2.5-9(13)cm x 0.15-0.4(0.9)cm, usually equal and terete [round in cross-section], occasionally flattened and then somewhat sulcate [grooved], sometimes flared at top and base, pliant and tough, becoming hollow; pale cinnamon in lower part, paler in upper part; dry, "usually minutely pubescent at first, becoming densely pubescent to strigose hispid" when old or when dried in place, sometimes nearly bald in upper part, pubescence whitish buff to pale grayish, white mycelium at base, (Halling), 3-10cm x 0.2-0.5cm, equal, hollow, sometimes flattened or grooved, pliant, tough; usually darker than cap (reddish brown), but covered with a minute white pubescence (use hand lens), base often with a lot of white mycelium visible in duff, (Arora), top of stem widens to form a small "button" that is easily separable from the cap (Kibby)

Odor:
mild, rarely with slight alliaceous odor, (Halling), odd, distinctive ?buggy, (Phillips), initially cyanic then garlicky, (Lincoff(1)), curious aromatic odor that is quite pleasant (Kibby)

Taste:
mild (Halling), mild (Phillips)

Microscopic spores:
spores 7-9.2(10.8) x 3.5-4.2(5) microns, elliptic in face view, slightly lacrymoid [tear-shaped] to elliptic or subfusoid in side view, smooth, inamyloid, acyanophilic; basidia 4-spored, 22.4-26.6 x 5-7 microns, clavate, not siderophilic; pleurocystidia absent, cheilocystidia conspicuous, 27.5-70 x 2.8-5.6 microns, "irregularly clavate cylindric, flexuous contorted to strangulated, sometimes irregularly lobed or forked"; clamp connections present in all tissues, (Halling), spores 7-9 x 3-4 microns, narrowly elliptic, smooth, inamyloid, (Arora)

Spore deposit:
whitish to cream-colored (Halling), white or tinged yellow (Arora)