Either buy them in an asian super market or grow them on your own. (Photo below).

How to prepare: add them to your skillet, put a splash of how water in it and put the lid on. Cook them for a few minutes, then lid off, and some (I prefer A LOT) of butter and spices. Sometimes, depending on the kind of mushroom, only salt and pepper (high quality ones), sometimes onions or garlic, whatever you want.

Prepared dish (Pheonix oysters) 1000016128

The same Pheonix oysters I grew 1000016114

Brown Shimeji on my balcony in a tub (cloned from the asian market) 1000015945

Lions Mane I grew 1000009189