My personal view on wild mushrooms is best described by my reaction to a British Mycological Society beautifully illustrated pamphlet, where the authors unceremoniously brushed away the question of edibility of various wild mushroom species, preferring instead to admire their beauty. I promptly threw the pamphlet away. Edible mushrooms are called "edible" for a reason.
A big little word of warning, don't pick any mushroom unless you are either 100% certain you know what it is, or know someone who can tell you with the same level of certainty what you have.
Anyway, near Magic Wood in Switzerland we picked up a mixture of Lactarius deliciosus (Saffron milk-cap or Рыжик in Russian) and scrobiculatus mushrooms (Груздь жёлтый in Russian). The following week in Italy, we picked up some Lactarius resimus (Груздь настоящий in Russian).
The Lactarius species are generally considered mostly inedible and sometimes even poisonous in the West, with some exceptions (e.g. Spain) due to their taste.
What a load of hogwash, because in the East they are considered one of the best, technically-edible mushrooms. The qualification simply requires these mushrooms to be prepared properly, by first soaking in water, then blanching. Where I come from, the most common use for these species is to salt or marinade them, so they are available during the Winter months. As far as I can tell, this process is almost unheard of outside of Eastern Europe and Russia.
The actual process is quite simple, which I've distilled from a recipе in Russian and simplified to use in the field, while travelling:
- clean and (if large) cut the mushrooms
- soak in water overnight (change the watera few times)
- blanch in heavily salted water (~20g non-iodized rock salt/1kg of mushrooms) for as little as 5 minutes or as much as 20, skimming foam periodically
- drain and add to a clean jar with fresh brine with spices (e.g. peppercorns, bay leaves, etc.)
- compact lightly, pour a 1-2cm layer of vegetable oil on top to prevent contact with air, cover with lid and store in the fridge
In theory, the mushrooms can be eaten the next day, but for optimal flavour, should be left salting for at least a few weeks in the fridge. They can be eaten cold, or by frying with eggs, potatoes, etc.
Of course, everyone has their own ideas on how to best do this, but ultimately the only really "active" part of the process is the boiling in over-salted water. This is the bit that removes all the unpleasantness and changes these mushrooms from technically-edible to edible (and very good at that). The remainder of the process is arguably the same as for salting/pickling any other vegetables.