Mine currently has sweet potatoes and fennel growing in it. The fennel sprouted in the sprint from huge fronds I threw in there last fall. It looked like a hairy compost pile.
Also, google hugelkultur. It's a method of building really tall raised beds with layers of rotting wood underneath. Gets things moving fast in the spring because the roots are really warm. Of course, you have to water it more because it's very porous.https://www.google.com/search?q=hugelku ... 40&bih=978