Every summer, 40 million backyard farmers produce more food than they can use, while people in their communities go hungry. If only they could link up. Enter Gary Oppenheimer, 59, of West Milford, N.J. He was directing a community garden a couple of years ago when inspiration struck. In May 2009, AmpleHarvest.org hit the Internet, connecting food pantries and gardeners. In just 150 days, Rosie’s Place in Boston became the 1,000th pantry on the site, and the growth has continued. As of Labor Day, 4,188 pantries were listed, in all states. Oppenheimer says the nonprofit organization is actively seeking grant funding to sustain what has sprung up.