The green or brown cap of this agaric is moist and domed and flattening with age. It's surface has dark fibrils and is greasy in wet weather. It causes nausea if eaten.
pallid, yellowish with fine, brownish or tan, radiating fibrils; at first convex, becoming flattened, with broad umbo, slightly sticky. Flesh off-white, tinted yellow under the cap skin. Gills
whitish ochre, emarginate, very broad, crowded. Stem
coloured as cap, but more pallid, smooth, more or less equal or tapering upwards. It develops yellow flushes with age. The mushroom has no ring.
Tricholoma portentosum has darker hat, and Tricholoma arvernense grows in coniferous forest. The poisonous Amanita phalloides is distinguished by it's volva, stem ring, and free gills.
on the MushroomExpert.Com Web site.