How to tell Agaricus squamuliferus from Yellow stainer

Cap 4-9 cm across, hemispherical to egg-shaped when young, becoming convex-flat with age. Color whitish to grayish-cream, with fine brownish or gray-brown radially arranged scales, a distinctive feature of the species. There are more scales in the center and fewer toward the cap edge. The surface is dry, not slimy.

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 (not attached to the stem), crowded. When young they are pink (a characteristic feature of the genus Agaricus, unlike the white gills of amanitas), and with age they become chocolate-brown to dark brown. 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 5-10 cm tall, 0.8-1.5 cm thick, cylindrical, slightly thickened at the base. Color white to cream. A white membranous ring in the upper part, distinct when young; in older mushrooms it may slip down or dry out. Above the ring the stem is smooth, below it has fine lengthwise fibers.

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, white; when cut it slowly turns pinkish to brownish, especially in the lower stem. This is the classic protective feature of the genus Agaricus against Amanita. In amanitas the flesh does not change color. Pleasant mushroomy smell with an almond note.

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.

Pleasant and mushroomy, with a subtle almond-anise note, typical of many Agaricus species. It does not smell of ink, medicine or carbolic (if it does, it is the yellow stainer: do not eat it).

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.