By Debra Samuels GLOBE CORRESPONDENT  MAY 12, 2015 SOMERVILLE — Ginger Chen scans the terrain, a sharp knife at the ready. A wide smile spreads across her face as she spots something. She bends down, pokes the knife into the dirt, and wiggles loose a straggly plant. This is no ordinary, unwelcome weed. At the edge of … Continue reading This Chinese grandma forages and cooks