You could try in a Northern forest! (Just kidding) Wild Blueberries are "cousin" with the cultivated blueberries, they are nowadays cultivated to, but it's genetically different a bit, as for the taste, the nutrients and the size. The cultivated ones have been modified (from a long time ago) to grow bigger and faster without having to burn the plants every two or three years (but now they just cut them two inches high from the ground, it's better and safer), the wild ones are longer to grow, but so much better for the taste and health, here we have many medicines coming from it! So to come back to your question: Sincerely, in California, I don't have the slightest idea where it could be found... But you can order it from Canada or, in U.S. from the Maine. If you ever (maybe) travel there you really should try them!!!