She started a trend
An increasing number of prisons are launching gardening programs: on-site gardens improve the nutritional intake of inmates and as a direct result can reduce violence and improve participants' mental health, teaches horticultural skills that can be used upon inmates' release (slashing recidivism rates), and also often produce surplus that is sent to food banks or other community centers or services. Here's just a sampler of such programs that have started since Sneed's Garden Project, or even before.
The Insight Garden Program, also in the Bay Area, runs a 1,200 square-foot organic flower garden at the the medium-security San Quention Prison, where classes are given to teach inmates about gardening, environmental sustainability, and community care through gardening.
Farther down the coast, the California Institute for Women runs an organic garden that sends fresh produce straight to the prison kitchen and the hospital kitchen, and is also geared to establish connections between the women and the outside community.
The Greenhouse Project on New York's Riker's Island has seen tremendous success, while in Wisconsin, 28 adult correctional institutions started on-site gardening projects last year. Each facility is producing thousands of pounds of vegetables per year—the highest yield being 75,000 pounds of produce, a quarter of which is donated to local food banks.
Inmates at Washington State's McNeil Island Corrections Center have transformed an acre of lawn in the middle of the facility into an organic vegetable patch filled with tomatoes, peppers, pumpkins and other plants—and composting units. The state has several other prison gardens that send produce to local food banks.
Greenleaf Gardens runs a Prison Horticulture Vocational Program in New York's Westchester County, where produce from a one-acre garden that is maintained by inmates is distributed to people in need in the area.
Prison garden projects exist in New Zealand and London and no doubt in numerous countries in between. There's even a how-to book about it (although it's out of print), and some programs have ways the outside community can get involved. So if you're looking for a way to green your neighborhood...