Never eat a wild mushroom identified only from a website, a book or an app. Have every find checked in person by an expert, such as a mycological society.
Identification
The ivory funnel is small and inconspicuous. The cap is flat to slightly depressed, sometimes with a wavy margin, and covered with a chalky white, frosted bloom that can crack or wear off in dry weather, revealing a faintly pinkish-buff or greyish surface with water-soaked patches. The gills are crowded, white to cream, attached to the stem and often running slightly down it. The stem is short and white to buff, with no ring or volva. The spore print is white.
DNA studies have shown that Clitocybe rivulosa, long treated as a separate species and known as the fool's funnel, belongs to the same species, so the two names are now often treated as synonyms. The placement of Clitocybe within the family-level classification of Agaricales is still being revised. Spores are small, smooth, ellipsoid and inamyloid; many small white grassland funnels look alike, and microscopy is often needed to name them.
Habitat and ecology
Clitocybe dealbata is a saprotroph that decomposes organic matter in grassland soils. It grows on lawns, pastures, meadows, parks, playing fields and grassy road verges, singly or in groups, and often forms rings or arcs. It is widespread in Europe and North America and fruits from summer to late autumn. It shares its habitat with the fairy ring champignon and other edible grassland mushrooms.
Uses and importance
This species has no food use. It contains muscarine, an alkaloid that mimics the neurotransmitter acetylcholine at muscarinic receptors of the parasympathetic nervous system. The toxin was first isolated from the fly agaric, but in practice small white Clitocybe and many Inocybe species contain far more and are the usual cause of muscarine poisoning. The ivory funnel is studied in toxicology and is a frequent example in foraging-safety training, because it grows where people least expect danger: in their own gardens and local parks.
Safety and edibility
Poisonous. Symptoms usually start 15 minutes to 2 hours after eating and reflect overstimulation of the parasympathetic nervous system: profuse sweating, salivation, tears, runny nose, blurred vision with small pupils, nausea, vomiting, diarrhoea and abdominal cramps. Slow heartbeat, low blood pressure and breathing difficulty from airway secretions can occur in severe cases, and poisoning is especially dangerous for children, older people and those with heart or lung disease.
If anyone, including a child or a pet, may have eaten a small white lawn mushroom, seek emergency medical help immediately, even if they seem well, and keep a sample or photo. No preparation makes it safe.
If you suspect mushroom poisoning, call your local emergency number or poison centre straight away, even before any symptoms appear, and keep the remains of the mushrooms.
Look-alikes
The most dangerous confusion is with the fairy ring champignon (Marasmius oreades), which often grows in the same rings. The fairy ring champignon has a tan to buff cap, often with a central bump, widely spaced gills that do not run down the stem, and a tough, pliable stem that can be twisted without breaking; the ivory funnel has a chalky white cap, crowded gills and a short stem. The miller (Clitopilus prunulus) has a pink spore print and decurrent gills, and also has dangerous white look-alikes. The snowy waxcap (Cuphophyllus virgineus) has thick, waxy, widely spaced gills. The deadly fibrecap (Inocybe erubescens) also contains muscarine but has a brown spore print.
Around the world
Clitocybe dealbata is common in grassland throughout Europe and North America, including private lawns and public parks. Because it can appear in the same fairy rings as edible species, mycologists recommend checking every single mushroom in a ring, not just the first few.
