Not quite a pickled mushroom, and more than a marinated mushroom, this is the Italian preservation technique called sott'olio, which results in an especially meaty preserved shroom -- especially if you use porcini or chanterelles.
Some mushrooms dry and store better than others. Some of the varieties that dried well for me were; Black Trumpets, Chanterelles, Chicken Of The Woods, Hedgehog, Porcini, Yellow Foot, and Oyster mushrooms.
During a recent fall hike, my daughter and I stumbled upon two large clusters of mushrooms. Lovely, pale silvery brown, some as large as my hand, the mushrooms fanned out in a layered array from a downed ash tree. Edible? Oh please say yes.