How to tell Field mushroom from Yellow stainer

Cap 5–15 cm across, spherical in young mushrooms, then flat or slightly umbonate. The surface is white or slightly creamy and cracks in dry weather. Fibrous scales may appear as it matures. The margin is inrolled at first, then straight.

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.

Gills free (not reaching the stem), crowded, delicate pink at first, then bright pink, and chocolate-brown or blackish in mature mushrooms. The pink color of the gills is a key safety feature that distinguishes the field mushroom from poisonous species with white gills.

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 4–8 cm tall, 1–2 cm thick, cylindrical, solid, straight. White in color. A characteristic firm membranous ring in the middle of the stem. No volva.

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, turns slightly pink when cut or stays unchanged. It does not turn yellow (yellowing is a sign of poisonous species). The taste is pleasant and richly mushroomy.

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.

Smell pronounced, anise-almond with mushroomy notes. This is one of the most aromatic wild mushrooms. With cooking the aroma intensifies and can dominate the dish.

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.