I think this is becoming popular advice in HN and adjacent communities. I don't agree or disagree, and absolutely loved Pollan's book, but having a psychedelic experience can be a very different thing for someone in doldrums vs. serious clinical or chronic depression. Having dealt with both and invested a huge amount of effort into escaping and avoiding the latter category at all costs, I think there's not a lot of actionable advice that applies to a person in that state, other than try to take care of yourself and hold on for dear life.
That being said, I've pursued this in the past and didn't really know heads from tails about where to get these substances or how to know they were safe, how to properly measure dosage etc. And I still don't. But I did learn that it is actually pretty easy to grow your own psylocibin mushrooms. I have had some interesting experiences with them, a novel break from ordinary life and mind. But in my experience, not a novel break from or treatment for depression; I would be ambivalent about having those experiences, especially a powerful one, in the midst of very dire emotional states.
That being said, I've pursued this in the past and didn't really know heads from tails about where to get these substances or how to know they were safe, how to properly measure dosage etc. And I still don't. But I did learn that it is actually pretty easy to grow your own psylocibin mushrooms. I have had some interesting experiences with them, a novel break from ordinary life and mind. But in my experience, not a novel break from or treatment for depression; I would be ambivalent about having those experiences, especially a powerful one, in the midst of very dire emotional states.