There are many tasty vegetables that can be planted in the warm season (about March through September) and in the cool season (about October through February) in California. Click here for a planting guide which lists the vegetables and the recommended planting dates.
There is also a very useful site for vegetables, Vegetable Research and Information Center (VRIC). This site gives detailed information about varieties, cultivation, problems and management for many different vegetables for the home garden. Click on the name of a vegetable and then look for the link to 'Home Garden' on that page.