I think it is pretty much impossible to buy Lactarius deliciosus, but the Russians and Poles also use porcini, honey mushrooms, chanterelles, russulas and, yes, regular button mushrooms. Not sure why, but most sources say to ferment only one variety of mushroom per batch. I pickle my mushrooms in a one-gallon stoneware crock, but you could use any non-reactive container. Store them in brine in a quart mason jar in the fridge for several months.
3to 4 pounds fresh mushrooms,cleaned and stems removed
Kosher or pickling salt
6to 10 juniper berries, crushed(optional)
1teaspoondried dill,or 2 tablespoons fresh
2teaspoonscracked black pepper
Boil the mushrooms in salted water for 5 minutes. Drain and let them cool in one layer on a paper towel or tea towel.
Mix all the herbs and spices in a small bowl. Lay down a thin layer of pickling or kosher salt at the bottom of a crock or other non-reactive container, then lay down a layer of mushrooms. Sprinkle with some of the herbs and spices. Add a bit more salt. Keep layering like this until you have all the mushrooms in the crock. Finish with another layer of salt.
Place a clean plate or other top on the mushrooms and weigh it down. I use a quart Mason jar filled with water. Let this sit in a cool, dark place (no need to refrigerate) for 4 days. After the first day, check to see that the mushrooms are submerged in their own brine. If not, boil 1 pint of water with 2 tablespoons kosher salt and let it cool. Pour over the mushrooms and continue fermenting.
After 4 days, move the mushrooms and brine and spices to clean Mason jars and refrigerate. They will keep for several months.
Note that prep time does not include fermenting time.