Because our climate stays above freezing (except for a couple of nights in january and february) it's safe to plant vegetables in the Fall. When planting them in containers you want to make sure to fertilize (or add worm castings to keep the soil rich enough to support the plants. You also want to make sure that your pots have good drainage otherwise the roots will start to rot and your vegetables will not be happy.
Try some of these, they're hearty and perfect for planting in the Fall:
beets, peppers, green onions, beans, lettuce, broccoli and radishes.
You can start them from seed or find baby plants. But either way make sure you read the details of how big the plant gets, how much sun it needs and much depth they need in the container to make sure you put them in the right spot.
Try flaxes and grasses that are either native to california or perfectly suited to our climate. We love Jack Spratt flax and also succulents. For some inspiration we were going to check out the California Cactus Center or the Theodore Payne Nursery. Remember this teeny tiny succulent garden? Totally inspiring.
Try some cool weather annuals like pansies, snapdragons, stocks, primroses, or cyclamens. This is also a great time to start planting springtime bulbs (see Sunset's top 5 favorite bulbs to plant in the Fall)
This is a great time to start your windowsill herb garden. We keep basil, 2 different kinds of thyme, rosemary and Italian parsley.