Africa's food systems are a final frontier for multinational food companies and retailers. Most Africans still consume a healthy diet of traditional foods, supplied by millions of small vendors and small farmers across the continent. But this is slowly changing as global food companies and retailers adopt new strategies to expand their presence on the continent, led by the aggressive actions of some multinational supermarket chains.

Across the U.S.—from New England to California—a small but growing movement of farmers is foregoing traditional farm ownership in favor of a cooperative model. In Maine, four Somali Bantu refugees raise crops on shared land at New Roots Cooperative Farm, growing both regional and Somali produce. To the south in Vermont, Intervale Community Farm shares farm ownership with its community supported agriculture (CSA) members.

Kriss Marion wasn't planning to become a farmer when she moved to Blanchardville, Wisconsin. The goal was to get out into green space with her family and be around farms, she tells CNBC Make It.

For nearly two years, a man tilled an overgrown park in a half-abandoned Detroit neighborhood into a tiny urban farm, filling the earth with the seeds of kale and spinach and radishes. He was black. The man was the subject of dozens of calls to the police by three women who lived on a street facing the park. They were white.