You got to find a local foraging group or just knowledgeable individual. If it's edible someone is eating it. But practical foraging is dominated by local concerns like microseasons, regional land/industrial history, soil & water quality etc.
For those in the Bay Area - Kirk Lombard author of The Sea Forager's Guide to the Northern California Coast (at least used to) do some guided tours harvesting flora and fauna of the Norcal coast. Enjoyable and informative. Here's the book
