How to identify it?
Cap
Cap 2-6 cm across, convex, becoming flatter with age; pale sulfur-yellow, becoming orange-tan toward the center; surface smooth but with marginal veil fragments. Flesh thin, quite firm, yellow. Taste bitter, not bitter after cooking.
Gills
Gills adnate, yellow, becoming greenish gray to purplish black in age, crowded.

Scientific Classification

Phylum
Club fungi Class
Mushroom-forming fungi Order
Gilled fungi Family
Hymenogastraceae Genus
Hypholoma Species
Sulphur tuft