The young, heart-shaped leaves of American Linden (Tilia americana) -- also known as Basswood -- can be eaten like lettuce, straight from the tree. Indeed I sometimes call this species the Salad Tree. Lindens often send up shoots near the base of old trunks, making tender leaves easy to gather. Older leaves are not harmful, they simply develop a less desirable texture. By late June or early July (in New England), the tree's fragrant flowers can be gathered and used fresh or dried for a medicinal tea.