Pleurotus ostreatus Product of California Top-quality Tree Oysters have been the focus of our farm for many years. We pride ourselves on producing some of the best organic mushrooms on the West Coast. A small portion of our fresh harvest goes to producing this high-quality dried tree oyster, which is lightly sweet and buttery. Tree Oysters are one of the most versatile mushrooms and can be used in any application in which crimini or porcini is called for.