>>448771In my experience, strawberries are about the easiest things to grow. They're pretty hardy and they proliferate through creeping runners which you can let spread throughout their section. Keeping them within their confines is as easy as scooching the runners back into their area if they start to spread out too much.
As for some other fruits, you might try watermelons. I don't actually have any experience with them, though. I hear they're a little more difficult than strawberries are.