Egghead mottlegillPanaeolus semiovatus

The egghead mottlegill (Panaeolus semiovatus) is a pale mushroom that grows straight out of horse or cow dung in pasture. It's easy to recognise by its cap, shaped like half an egg, its black gills and the thin ring on its long stem. It's the only common mottlegill with a ring. It used to be placed in a genus of its own, Anellaria, so older books may list it under that name. It's also called the shiny mottlegill. James Sowerby described it from England in the 1790s, and semiovatus is Latin for half an egg.

How do you identify an egghead mottlegill? The cap is 2 to 6 cm across, sometimes up to 9 cm, egg-shaped when young, then like half an egg or a blunt cone, and only rarely flattening out. It's whitish, cream or pale clay-coloured, darker in the centre. When wet it's sticky; when dry it's shiny and often wrinkled or cracked. The gills are attached and crowded, greyish at first, then mottled with black patches and finally black, with pale edges. The spore print is black. The stem is 6 to 15 cm tall and 3 to 10 mm thick, long and slender, pale and finely powdery at the top, and brittle. Above the middle there's a thin white ring that turns black on top from falling spores. The ring can drop off, and a rarer, slimmer form has no ring at all, so a missing ring doesn't rule this species out.

Where does it grow? Almost always on dung, mostly horse and sometimes cow, or on freshly manured ground: in pastures, grazed commons and upland meadows. It grows singly or in small groups from late spring to autumn. It's fairly common, mainly from spring to late autumn with most records from late summer to autumn, and odd ones turn up in mild winter spells.

Is the egghead mottlegill edible? No. Some old guides called it edible and others poisonous, so there's no reliable verdict, and it's thin-fleshed and grows on dung. It also has a reputation as a hallucinogenic mushroom, but laboratory analyses of the samples tested, published in 1985 (four collections) and 2026 (a specimen from China), found no psilocybin in it. If someone may have eaten an unknown mushroom, get help straight away, even if they feel fine: call emergency services on 112 (999 in the UK) or your local poison centre and keep any leftovers. With the deadliest species, symptoms may only start 6 to 24 hours later.

What can you mistake it for? The petticoat mottlegill grows on dung too, but it's smaller and grey-brown, has no ring and has white tooth-like scraps around the cap edge. In the same horse paddocks you'll find edible field mushrooms and horse mushrooms. They also have pale caps and a ring, but their gills are pink (greyish white at first in the horse mushroom), then chocolate brown, their spore print is dark brown, their flesh is thick, and they grow in grass rather than on dung. So before picking field mushrooms, check the gills and take a spore print. The garland roundhead has a yellow cap and a purple-brown spore print, the spring fieldcap has brown gills and a brown print, and the stubble rosegill has pink gills and a sac (volva) at the base. Outside our catalogue, the closest lookalike on dung is the dung roundhead (Protostropharia semiglobata), which is smaller and yellowish with a purple-brown print. And the small ringed Conocybe rugosa is deadly: it's brown with a rusty spore print and grows on wood chips and flowerbeds, but it's a good reason never to eat small ringed mushrooms from lawns or pasture. And pale ringed mushrooms with white gills, a white spore print and a sac at the base may be deadly amanitas: never pick those.