Garland roundheadStropharia coronilla

The garland roundhead (Stropharia coronilla) is a small yellow mushroom of meadows, pastures and lawns, and it is best left where it grows: most modern field guides list it as poisonous, although no toxin has ever been identified. Look for a smooth yellow cap, lilac-grey gills and a white stem carrying a small ring with fine grooves on its upper side. That grooved ring, like a little crown, gives the species both its Latin and its English name.

Most of its relatives live on wood chips, straw or dung, but this one grows straight out of the grass. You'll find it singly or in small scattered groups in open, sunny places: pastures, roadside verges, parks, gardens and lawns, on poor and well-fertilised soil alike. It is widespread across Europe and also occurs in North America. Fruiting runs from late spring to late autumn and peaks in September and October; around the Mediterranean it can carry on through mild winters into April.

Is it edible? No. Some older books called it edible, but its edibility has never been confirmed, and one poisoning is on record: in the 1970s two people in the United States ate a soup made from these mushrooms and within an hour developed a severe headache, nausea, poor coordination and hallucinations. The mushrooms were identified only from specimens picked at the same spot and from photographs, and the cause was never established.

Is it a magic mushroom? There's no evidence for it. Roundheads are close relatives of Psilocybe, so the claim keeps getting repeated online, yet no chemical analysis has ever found psilocybin in this species. A large 1985 screening of European fungi included Stropharia species, and none of them tested positive.

The real risk is mistaking it for a field mushroom or a horse mushroom in the same field. Those Agaricus species have free gills that are pink when young and chocolate brown later. The garland roundhead's gills are attached to the stem and lilac-grey, with no pink at any stage. The horse mushroom is also far larger, smells of aniseed and bruises yellow.