Most families in the Fifth World practice gardening to one degree or another, from tossing a few seeds down to extensively managing a forest garden. No one practices agriculture, with its reliance on grain and monocropping. And many of the supposedly wild jungle consists of revolving communities of food crops originally planted shortly after the collapse.
Because dense tropical rainforest covers most of the land, gardening most often involves slash-and-burn techniques to clear space and return nutrients locked up in hardwood trees to the soil. Today, we often think of slash-and-burn as environmentally destructive, but people who practice it do so very sustainably. Toby Hemenway describes the process well in his article, "Seeing the Garden in the Jungle."
Once they have burned a plot, they plant a regular cycle of permaculture guilds (i.e., plants that grow well together) that, over the course of a generation or more, mimics the natural process of succession. As one plot (or milpa) goes through these stages, they move on to another, allowing each milpa to fully recover before burning again. In this way, a cultivated forest maintains a great deal of biodiversity and resilience.