The right wild mushroom species have a richness of flavor with which no cultured mushroom can possibly compare. They are high in iron and selenium, low in calories. They are an excellent source of vitamin B. A vegetarian diet can use mushrooms to substitute for meat.
However, the wrong wild mushroom species can be deadly. The earliest symptoms of the common Aminita toxin alpha-amanitin, diarrhea and cramps, don’t appear until 10 or more hours after eating the mushroom, which is too late for stomach pumping. The most serious effects of alpha-amanitin don’t appear at all until 4 or 5 days after eating the mushroom, when the liver and kidneys start to fail. Even today, people often die from mushroom poisoning.
The main identifying features of a mushroom are the color and shape of its cap and stem, the universal veil, and the color of its spore print. Spore prints should not be confused with water dripping down through the gills. Older mushrooms may not leave a spore print. Immature mushrooms often look different from the mature pictures in nature guides.
Unfortunately, there is no absolute broad rule which says clearly which mushrooms are good to eat and which mushrooms are poisonous. Folklore is not a reliable guide. Bright colors are found among both poisonous and safe mushrooms. Many dangerous mushrooms are dull brown or white, just like the safe ones in supermarkets. Some safe mushrooms have pointed caps, and some poisonous mushrooms have flat, rounded caps. Even cooking or pickling a mushroom won’t necessarily make it safe.
For example, nearly all aminita mushrooms are extremely poisonous. Approximately 95% of all fatalities due to eating mushrooms are caused by Aminita mushrooms, especially Aminita phalloides, the death cap.
Some Aminita mushrooms can be identified by their bright red caps. The classic toadstool, with its white-spotted red cap, is aminita muscaria, commonly known as fly agaric. That one is poisonous, but less poisonous than many other aminitas. It is also easy to avoid.
However, the death cap and the destroying angel, its cousins in the aminita genus, are white or brownish white, and closely resemble various edible mushrooms. Immature aminitas are often confused with edible puffballs. To make matters worse, death caps have been reported, by people who have eaten them, to have a good taste.
The safest way to avoid mushroom poisoning is to avoid any mushroom which has not been identified by an expert. If you don’t know what you are looking for, don’t take a chance.