Top 20 Most Common Toxic or Poisonous Mushrooms in Redwood City

1. Western jack-o'-lantern mushroom

The western jack-o'-lantern mushroom (Omphalotus olivascens) may be the most visually striking mushroom of the forest during day and night. During the day, brilliant large orange flat caps grow from both the ground and decaying stumps. At night, these mushrooms may glow in the dark, depending on location and maturity.

2. Sulphur tuft

The sulphur tuft grows on rotting wood of all types of trees; it is a particularly efficient decomposer of hardwoods. The mushrooms appear from spring to autumn and are often so tightly packed that they interfere with each other’s shape. This poisonous mushroom can cause temporary paralysis, distorted vision, and stomach pain if consumed.

3. Yellow stainer

The yellow stainer grows across North America and Europe and has been imported to Australia. It can be distinguished from other common white mushrooms by the bright chrome yellow color it turns when bruised. It is known to be poisonous, causing cramps, nausea, and purging. Unfortunately, it often gets accidentally eaten as it looks similar to several edible white mushrooms.

4. Shaggy parasol

The shaggy parasol grows singly or in groups from spring to fall. It can be found in lawns and gardens as well as the forest. It has a tendency to cause allergic reactions. Take care with identification as it is difficult to distinguish from the more deadly Amanitas.

5. Oak-loving elfin saddle

6. Mower's mushroom

The mower's mushroom, also referred to as the lawnmower's mushroom, is so named because it frequently crops up in lawns. The species is rather nondescript, and it is considered a member of the infamously hard-to-distinguish "Little Brown Mushroom" (LBM) family. While the mower's mushroom is not known to be toxic to humans or dogs, several of these close look-alikes are.

7. Yellow-staining milkcap

Like most other milkcaps, the yellow-staining milkcap will ooze a white, latex-like substance when cut or otherwise damaged, but, unlike closely related species, the latex of this mushroom will quickly turn canary-yellow when exposed to the air. Go ahead and try it out for yourself, but don't take this one home to the kitchen! The yellow-staining milkcap is toxic.

8. California agaricus

The california agaricus, found along portions of coastal California, is a toxic mushroom that is closely related to (and closely resembles) several sought-after, edible species, such as button mushrooms and white and brown field mushrooms. One distinguishing characteristic of california agaricus is that its flesh will begin to yellow when cut or bruised; unfortunately, this reaction is not always obvious. It is not deadly poisonous, but ingestion can cause gastrointestinal distress.

9. False chanterelle

The common name of this mushroom refers to the fact that it looks very similar to the edible and highly prized Chanterelle. This species, however, tastes bitter and may cause poisoning symptoms. False chanterelle occurs around the northern hemisphere in autumn and winter, growing on coniferous detritus, and is more likely to fruit in dry conditions rather than the usual wet.

10. Wolf lichen

The thallus, or vegetative body, has a fructicose shape — that is, shrubby and densely branched — and a bright yellow to yellow-green, or chartreuse color, although the color will fade in drier specimens. Its dimensions are typically 2 to 7 cm (0.8 to 3 in) in diameter. The vegetative reproductive structures soredia and isidia are present on the surface of the thalli, often abundantly.

11. Panther cap

Named for the brown-and-white spotted pattern on its upper surface, the distinctive panther cap grows under hardwood trees, particularly oak and beech, and also under Monterey pine in urban areas or forests. It contains a cocktail of poisonous toxins with the potential to be deadly.

12. Black bulgar

The black bulgar is an unusual fungus that looks a bit like black gumdrops. While some authorities classify it in an "unknown edibility" group, others claim it's a poisonous mushroom. Either way, its unappealing appearance surely makes it an easy choice not to consume the black bulgar.

13. Large white Leucopaxallus

Large white Leucopaxallus (Leucopaxillus albissimus) has been bestowed with the title of "whitest mushroom" by mycologists around the world. The pure white cap is rotund in shape and sits on a stem that is equally as bulky. This mushroom lacks luster and can reach up to 15 cm wide. Unlike many other mushrooms, this one does not change its color as it matures.

14. False parasol

Though the false parasol appears unassuming, the species is famous—or, infamous—for its toxicity. It looks unfortunately similar to Agericus campestrus, a commonly eaten mushroom, but the false parasol can be distinguished by its highly unusual green spore print. Although they are no good to eat, they can be pretty to look at. The species may grow in ring-shaped groups in meadows and on forest floors in what are sometimes called "fairy circles."

15. Flowerpot parasol

This tropical/subtropical mushroom is known to be toxic. If eaten it causes a very unpleasant stomachache with the risk of fatal complications. In temperate zones, flowerpot parasol is only found in hothouses and greenhouses, so the risk of accidental foraging is low, but it may occur with potted plants and indoor landscaping and pose a risk to curious children.

16. Fragrant funnel

This delicate little mushroom grows on the forest floor in deciduous woodlands. It can also be seen sprouting up by roadsides, under hedges, or in parks and lawns. While there are many varieties of small white mushrooms in this habitat, only the fragrant funnel smells so sweet; its fragrance is similar to anise. Despite this, it is reported to be poisonous.

17. Poison pie

This toxic mushroom blooms on conifer and broadleaf forest floors around the northern hemisphere. It can appear singly, in tufted groups, or in fairy rings. The poison pie can be distinguished from its close relatives by the dark brown watery droplets that form in its gills. As the common name, "poison pie" implies, it is seriously toxic.

18. Pine cone Amanita

The elongated cap of the pine cone Amanita (Amanita magniverrucata) is smothered in a warty surface, with the peaks of those warts appearing darker in color. It has a very pungent odor, and although it is not toxic, this makes it quite unpalatable. The tell-tale fragrance is not present during all growth stages, so this should not be relied upon alone for identification.

19. Creamy russula

The creamy russula is so-called because is one of the unusual species that fruits during winter. The species' range, the wet, northwestern coast of the United States, stays cool but rarely dips below freezing during this time. Red-capped and white-gilled, creamy russulas look very similar to a host of other russala species; this species is just bitter-tasting, but some of its look-alikes are toxic.

20. Oyster rollrim

The oyster rollrim lacks a stem, and its lightly fuzzy orange cap, which can grow to a width of 8 cm, will bald with age. This fungus grows in conifer woodlands throughout North America and Europe, from spring to late fall. It has no odor and is poisonous.

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