How to tell Horse mushroom from Yellow stainer

Cap 6-20 cm across; in young mushrooms firmly hemispherical to egg-shaped, the margin often rolled under. Later it becomes convex to flat. Color pure white to cream, with subtle yellowish tints in old mushrooms; spots yellow to ocher when touched. Surface smooth, slightly sticky in wet weather, dry and matte in dry weather. Sometimes with fine fibrous scales in the center.

Cap 5-15 cm across; in young mushrooms firmly hemispherical to squared-off (a characteristic feature — the "square" young cap), later becoming convex to flat. Color white to cream, sometimes grayish-brown in the center. The most characteristic sign — touching the cap or its margin leaves bright chrome-yellow spots, especially noticeable in young mushrooms. The surface is smooth, slightly sticky in wet weather.

Gilled hymenophore — gills free, crowded. When young — grayish-white, with a pinkish tinge, becoming with age dark brown, chocolate-blackish. Spore print dark brown.

Gilled hymenophore — gills free, crowded. When young — pale pinkish-gray, becoming with age dark brown, chocolate-blackish. Spore print dark brown. The gill color is typical of Agaricus — it doesn't help tell the yellow stainer apart.

Stem 6-12 cm tall, 1.5-3 cm thick, thick, fleshy, cylindrical, slightly thickened at the base. Color white to cream. On the upper part — a large membranous double ring with a characteristic "toothed" lower edge (like a cogwheel) — a diagnostic feature of the species.

Stem 5-12 cm tall, 1-2 cm thick, cylindrical, with a pronounced bulbous base (a difference from other Agaricus species, whose stems are more even). Color white. The most important diagnostic sign: when cut, the flesh at the base of the stem and in the bulb is bright chrome yellow, often almost neon, and the reaction is fast (10-30 seconds). On the upper part — a white membranous ring, distinct in young mushrooms.

Flesh firm, meaty, white; when cut it slowly yellows in the flesh of the cap and upper stem. Does not redden (unlike A. silvaticus). The smell is a distinct anise-almond — a characteristic feature of the species.

Flesh firm, white in the cap and upper stem, bright yellow at the base of the stem even when undamaged. When cut, THE BASE OF THE STEM TURNS BRIGHT CHROME YELLOW — the main diagnostic sign. The cap yellows too, but more weakly. The smell is distinct and unpleasant — ink, phenol, medicinal ointment, creosote.

Distinctly anise-almond, fruity — the most characteristic diagnostic sign. It comes out when you rub the flesh between your fingers. This smell is one of the most pleasant mushroom experiences in field foraging.

Distinct and unpleasant, with notes of ink, phenol, medicinal ointment, creosote, printer's ink. It comes out when you rub the flesh between your fingers, especially at the base of the stem. This smell is the most reliable sign: no edible Agaricus smells like this.