I teach lichen ID workshops and field walks periodically in the SF Bay Area and beyond–you can find details of upcoming events on twitter.
Lichen resources and groups
Checklist of North American lichens – The authoritative species list for the continent, updated periodically.
California Lichen Society – California’s finest (and only) lichen organization. Join the listserv too to stay in the know about exciting lichen events.
Ways of Enlichenment – Read Trevor Goward’s fascinating essay series. You’ll never see lichens the same way again.
Back issues of the Bulletin of the California Lichen Society – Lots of interesting articles, field trip reports, etc.
Northwest Lichenologists – Arguably the energetic centroid of the North American lichen scene!