Foragers and farmers see native-grown hickory nut oil as a sustainable alternative to environmentally harmful imports.By Jessica KleinIf you’ve ever looked for a homegrown replacement for the imported olive, canola and palm oils that typically fill grocery store aisles and home kitchens, there’s a small but growing alternative. A network of sustainability enthusiasts is now making oil from a resource native to Pennsylvania, one of the fastest-growing hubs for this production—bitternut hickory trees.