A growing number of recreational users of psilocybin mushrooms in New England are attempting to turn their passion for the fungi into a broader movement, while campaigning for local measures that would legalize the use and cultivation of the plants.

About 40 minutes after swallowing the plants, the effects began to set in. Davis and McGurk, self-described mushroom nerds, talked of becoming more lucid and focused as they scoured the woods for wil…