The mushroom of longevity or immortality the Chinese speak of is Ganoderma lucidum, the Reishi mushroom. It is actually a wood fungus, not a mushroom in the fairy circle context. All edible mushrooms (reishi, shitake, miatake, button, et.) are considered medicinal to some degree but the Reshei is the king. A great longevity tonic is reshi wine (six parts wine to one part reshi, soak for a month and drink 2 ounces per day). Mushrooms are one of the herbs that are most easily processed into kidney essence and then to Shen (through Practices), and are considered one of the so called spirit foods because of this. Psychedellic mushrooms convert almost immediatly to Shen and because of this one percieves the world of the Shiens immediatly and directly. However, the experience does not last because 1. the mushrooms energy is so rarified and 2. there is usually no practice to support the experience. You get to look through the window but you can't open the door and go in because you have not done the work. The other way, with the Reshi combined with Practices, you eventually get to go in and stay.