How to tell Leucoagaricus nympharum from Stinking dapperling

Cap 4–10 cm, egg-shaped at first, opening out flat with age, with a low, barely raised, pale brownish umbo in the centre. It's white, covered in fibrous white scales: the typical "parasol" texture.

The cap is 1.5–5 cm across, occasionally up to 6. Young caps are bell-shaped or bluntly conical, then convex, later flattening, often with a low central bump. The surface is dry, not sticky.

The background is white or cream. The tawny, orange-brown or reddish-brown skin breaks up into small scales as the cap expands. They lie in concentric rings and thin out towards the edge. The centre stays a solid, smooth dark patch, and this 'eye' on a pale cap is usually the first thing you notice. The margin is sometimes finely lined.

Gills crowded and free (not attached to the stem). White at first, taking on a faint pinkish tint with age; they darken when pressed. Spore print white.

The gills are free, meaning they don't reach the stem, crowded, with short gills in between. They are white or cream and darken only slightly with age.

The spore print is white to creamy. Pink or chocolate gills mean it isn't a dapperling but, for example, an Agaricus mushroom. Even so, a white print doesn't make a small parasol edible.

Stem 5–12 cm tall, 0.5–1 cm thick, slender and cylindrical, with a bulbous base. White, with a broad, movable milky-white ring.

The stem is 2–7 cm tall and only 2–5 mm thick, even or slightly thicker towards the base, smooth, silky, hollow and fragile. It's whitish or cream, pinkish or brownish towards the base, with white mycelial fluff at the very bottom.

The ring on the upper stem is white, thin, membranous and very fragile. Older specimens often have none at all, so a missing ring doesn't rule out a dapperling. There is no volva or sac at the base.

Flesh white, thin, tender. When cut, especially in the stem, it may slowly turn slightly pinkish.

The flesh is thin and white and doesn't change colour when broken. Field guides describe the taste as mild or unremarkable.

A faint radish smell. Mild taste, without distinct notes.

The smell is strong and unpleasant: sharp, like rubber, coal gas or chemicals, which is how it earned the name 'stinking'. Some people pick up something fruity or sweetish in it. The smell helps identify the species, but it doesn't make the mushroom any safer.