To my (far from expert) understanding, spore printing is going to be your best bet. I can't link you straight to some of the mushroom-centric forums that have writeups, but a quick google will elaborate upon the nuances.
The broad strokes:
Remove stem, hydrate the cap if it feels excessively dry, lay cap gills-down on some reasonably thick printer stationary (ie anything but bible or rolling paper), cover cap with a glass or mug; wait twelve hours.
The cap should drop the mature spores and form a vivid purple-blue outline clearly visible to the naked eye.
I've never had any success if finding psychoactive mushrooms, but the sport printing procedure hasn't failed to do what it's supposed to do, for me?
Good luck.