Water Lily: The leaf and unopened flower buds can be cooked, while the tuberous rootstock can be prepared like potatoes.
Field Mustard: From the leaves to the buds to the seeds, the entire plant can be eaten, just avoid the bitter upper-stem leaves.
Clover: Both red and white clover can be eaten. Reds should be soaked and boiled 5-10 minutes; white should be eaten before the flowers appear.
Burdock (pictured above): The young leaves and inner roots and pith (remove the green rind) can be eaten as a salad though the roots should be boiled first.
Staghorn sumac (pictured above): The red berry clusters can be soaked in cold water and, once strained, make a cold tea.
Pine trees: All variety of pine needles can be steeped to make a hot tea rich in vitamins. Young, male cones can be cooked in an emergency, and inner bark (as well as the inner bark of spruces and firs) used as flour.
Black locust (pictured top): The flower clusters may be dipped in batter and fried as fritters.
Wild fruits: Pennsylvania has a number of wild fruits such as grapes, strawberries, and raspberries that can be eaten fresh. Other fruits like elderberries require some cooking.
Wild nuts: Beech, chestnut, and chinquapin are all edible nuts that need only to be roasted to get at the kernels inside the outer husks.
Fiddleheads: So-called because of their shape, when taken off bracken and ostrich ferns they may be eaten as-is or boiled (recommended for the bracken). Do NOT confuse them with hemlock, which is poisonous. When in doubt, leave it.
Great Bulrush: Found in mud or shallow waters, the young shoots may be eaten as greens and the tips of the rootstocks may be prepared like potatoes. Pollen and seeds can be made into flour.
Mushrooms: There are edible mushrooms in Pennsylvania, most notably morels (pictured above) found in the spring. Only eat mushrooms you are 100% sure of.