Here's the science part.
The mushrooms contain two psychoactive compounds: ibotenic acid and muscimol. The former isn't that strongly psychoactive, other than inducing sedation and a generic delirium. It's also pretty toxic, and is used in clinical trials as a "potent brain-lesioning agent". Which isn't really what you want. Fortunately, you can turn it into muscimol, which is both much more psychoactive and much less toxic, by drying the mushrooms out. You can do this easily by cutting up the caps, spreading them out on a wire oven shelf, and heating them in an oven on its lowest setting with the door slightly open.
The stems have very little of these chemicals in them and should be discarded. Apparently the gills are mainly dead weight, too. So what you want is the cap flesh. Dry them out until they're properly crispy, but be sure not to cook them as such.