Pileus 4.0-6.0 (7.0) cm broad, campanulate in youth, becoming broadly convex to nearly plane, often with a low umbo; margin at first incurved, then decurved, occasionally wavy and rimose; central cap covered with a thin whitish veil, tinged blue-grey, overlying a brown, appressed-fibrillose to squamulose surface apparent towards the margin; context up to 5.0 mm thick at disc, whitish to pale pinkish-buff in some areas, bluish-grey below the disc; odor strong, similar to matsutake, or rotting pears; taste not distinctive.
Gills close, adnexed to notched, pallid, becoming dingy tan-brown, up to 7 mm broad; edges minutely scalloped, not distinctly lighter than the faces; lamellulae in three to four series.
Stipe 4.0-9.0 cm long, 1.0-2.0 cm thick, round, solid, straight, occasionally with a basal bend and small bulb; surface of apex pruinose when young, whitish, elsewhere finely striate, the lower portion covered with loose brown fibrils, bruising dark-brown where handled, the base often tinged blue-grey; context fleshy-fibrous, pallid, unchanging to slowly pale-brown; partial veil absent.
Spores 7.5-11.0 x 5.0-6.0 µm, smooth, moderately thick-walled, elliptical to almond-shaped in face-view, inequilateral, sometimes subfusiform, hilar appendage inconspicuous; spores olive-brown in deposit; pleurocystidia and cheilocystidia present but uncommon.
Solitary or in small groups in mixed hardwood/conifer woods, probably associated with oaks; found in the Coast Ranges and low to mid-elevations of the Sierra Nevada; fruiting after the fall rains; occasional.
To be avoided. One study has shown small amounts of psilcybin, another study showed no psilocybin, but the toxin muscarine.
Color and a distinctive odor make Inocybe corydalina relatively easy to identify. Fresh specimens have a central cap covered with a bluish-grey tinged veil and a concolorous stipe base. Combined with a strong "matsutake like" odor, it is unlikely to be confused with any other Inocybe except perhaps Inocybe calamistrata which has a bluish-grey stipe base but lacks the characteristic odor of I. corydalina. Inocybe calamistrata also differs in having a darker brown, more squamulose, veil-less cap. An Inocybe that does mimic the odor of Inocybe corydalina is Inocybe fraudans (=I. pyriodora). It is distinguished by an ochre-brown fibrillose cap lacking bluish-grey tones.