The great thing about living in California is the variety of fruit trees that can be grown. I read on one website that said not to expect to ever eat more than 500 calories per day from your garden. I suppose this is correct if all you are eating is vegetables. On the other hand, fruit packs a punch (in more ways than one). Fortunately those in my household can eat plenty of fruit and vegetables and it doesn't cause diarrhea.
In the morning I make a fruit shake. I can use an orange or two, a couple of peaches, plums, some grapes, or whatever the mood suits me. Mix it in the blender add a little ice and voila, a great shake that I didn't have to spend any money on. (It's better than jamba juice because the fruit came from the yard)
Each year for arbor day and each year for my birthday I plant trees. I have a good variety growing but expect to plant more varieties as the years go by. One of my favorite books is the Sunset Western Garden Book. I just skim through those pages and pick fruit trees and plants. Many of the types of fruit I'd never seen of until I grew them myself! Even if you don't have a big yard, you can grow semi-drawf or drawf fruit trees. Most fruit growers grow on semi-drawf or drawf root stocks. Right now we have about 60 fruit trees. If each tree gave us 100 pieces of fruit (and believe me, most years we get much more than that), and each fruit was 100 calories, we'd get 10,000 calories per tree. Doing a bit of easy math and you can see that my fruit trees would provide over 1500 calories of food per day every day of the year. You can easily put over 100 trees on an acre. In fact, if you were a fruit farmer you would more than likely plant over 200 trees per acre. Check out this website for some good basic information. http://www.thenewfruitgrower.com/training_systems.htm
I can some of my fruit, I freeze some of my fruit, and I dry a lot of my fruit. The kids love fruit roll-ups. This is a really lousy food that you buy at the store. It costs about a dollar for 1/2 a piece of fruit, some corn syrup, and artificial color and flavor. I make my own. Cook the fruit a bit to soften. Mash up the fruit, either using a blender, a grinder, or a pestle. You can sweeten it with sugar or honey. Spoon the fruit on plastic wrap. Stick it in the dehydrator, oven at the lowest setting with the door open, or in the sun (covered with an old sheet or screen to let the heat get to it but not the bugs). It's easy and so much better than the store junk. Of course, the kids will miss the pretty colors from the artificial coloring.