Just as John mentioned, I learnt my first mushrooms from my grandparents here in Germany, who went for mushrooms every year in August/September. It always was a fascinating weekend trip. Many people here are familiar with some basic species, they are certain about. These are mostly boletes, some agarics growing on wood (e.g.
honey fungus) and some special looking mushrooms like cauliflower mushroom (Sparassis crispa) and giant puffball (Calvatia gigantea). Not so many people are confident enough to collect other agarics.
Here are the basic rules I have learnt:
- Only eat mushrooms you can determine as edible without any doubt (or consult an expert).
- Leave the other ones in the wood.
- Don't collect the very old ones and the ones, that are already out of the ground. (These are often partially rotten. The same applies, by the way, for mushrooms lain around in a shop for two days or more.)
- Don't collect too young ones, that are not safe to determine yet.
- Clean them, if possible, directly after collecting in the wood. (I never did that, too much work...)
- Collect into airy baskets, do not use plastic bags. (They rot fast after squeezing or having condensed
water around.)
- Fresh mushrooms can be stored for up to two days in a fridge (airy, e.g. wrapped in paper) and another two days, after they have been cooked or fried.
- Never eat a mushroom raw, lots of otherwise edible ones are toxic in raw condition (not deadly, but can cause digestive problems).*
For collecting I think it is best to turn them out of the ground. This method does not harm the mycelium too much, in contrast to just pulling them out. Cutting them loose with a knife leaves parts of the stem in the ground, which act as an invitation for insects or bacteria to eat more of the mycelium.
For boletes (Wikipedia is good for following the section): Here, there are only two toxic ones (causing digestive problems: Boletus satanas, devil's bolete; Boletus calopus, bitter beech bolete; they have a light gray hat and red stem) and one inedible one (very bitter: Tylopilus felleus, bitter bolete; one small mushroom can ruin a whole meal). The others are all edible and taste usually great. The difference between the bitter bolete and the similar Boletus edulis (cep, we call them stone mushrooms, they look a bit like stones and have a nice, stable tissue) is the gray-pink sponge of the bitter bolete versus yellow-white sponge of the stone mushrooms. Also, tasting a small piece raw and spitting it out is not dangerous here.
Blue staining on cuts or on areas after pressure is not an exclusion criterion for toxic ones here in the area. There are some very good, edible ones that stain blue on cuts: Boletus badius (bay bolete); Boletus luridus und Boletus erythropus (in German Hexenröhrlinge = witch boletes), Boletus chrysenteron (red cracking bolete). The first three
should not be eaten raw, though.
The two witch boletes have also a red stem like the devil's bolete, that's why most people don't collect them. But the stem has a different texture, and their hat is brown.
All in all, there is very little danger, when only collecting boletes and frying them. The worst that can happen is heavy puking after having devil's bolete, the second worst a very bitter, inedible meal with the bitter bolete. I guess, the boletes are somewhat similar in the US, but of
course, please look up all toxic or inedible ones first. Probably there are some other ones to be careful about.
* I tried it several times with the cultured Agaricus button mushrooms and it seems ok, though. Here my concern would be bacteria from the growing medium (compost/horse manure).