How to Change Your Mind by Michael Pollan is a good overview of the current research and applications of psychedelics. Additionally though, it’s also a very interesting exploration into spirituality, mysticism, and the nooks and crannies of mind and consciousness.
We perceive the world around us with our minds. We know nothing else. Perturbing that mechanism a bit provides some useful insights into how it works in its “normal” state. It’s a toss up whether or not you’ll come away from this believing that humans are more than we think we are or less. It will provide some insight in either case.