I kind of lucked into both circles through high school friends, but it seems like the best way to get tapped into the local fests otherwise is through small artists and DJs on social media (usually instagram) whose work has shroomy vibes. This next part no longer applies to those of us in the Plague Zone, but local art shows, especially ones with augmented reality stuff, are also generally full of chill people. You could also six-degrees it, and figure out which of your normal friend's friends have friends, etc.