How to tell Parasol mushroom from Stinking dapperling

Cap large, 10-25 cm across. Egg-shaped at first, then opening flat like an umbrella, with a small blunt bump in the centre. The background is light grey to greyish brown, covered with large brown or greyish-brown scales in concentric rings; the centre is darker and smoother. The skin peels away from the flesh easily.

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, thin and free (they don't touch the stem), an important feature of the genus. White at first, turning cream to yellowish with age. 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 tall, up to 30 cm high and 1-1.5 cm thick, cylindrical, with a bulb up to 2.5 cm at the base (no volva: this is crucial!). Gray-brown with a distinctive “snakeskin” zigzag pattern of darker scaly patches, a diagnostic feature. Near the top is a fleshy movable ring that you can slide up and down, whitish above, with a brown edge below.

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.

The flesh of the cap is white and soft, juicy in young mushrooms, softer and a little limp in old ones. When cut, it stays white and does not change colour, an important difference from similar species. The stem flesh is tough and fibrous, not edible.

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

The smell is faint, with no distinctive notes. The taste is mild and sweetish.

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.