As fog catches in the trees, mushrooms materialize overnight, pushed up from an unseen network underground. In the fall, gold chanterelles glow against the moss under Douglas firs. Amid the vast kingdom of fungi, some are toxic, a few are prized in traditional medicine and some are simply delectable. Yet for all their mystery, mushrooms can be simpler to grow than you think.

Fungi are colonizing pop culture, from mushroom coffee to television. A parasitic fungus drives the zombie apocalypse in HBO’s “The Last of Us.” “Star Trek: Discovery” named the starship scientist who travels a cosmic mycelial network after Washington mycologist Paul Stamets. The poisonous red-and-white Amanita toadstool, a German symbol of luck, regularly adorns socks, candles and ornaments.

“There are absolutely days where you can come home and see your mushrooms, and you’re like, ‘That’s way bigger than it was when I left 8 hours ago,’” says Mark Rickard of Skagit Gourmet Mushrooms , based north of Sedro-Woolley.…