The hickories (Carya), which include the Pecan, are remarkably similar to the walnuts. But here I think you are being too clever. The hickories most likely to be seen here have a much more pointed end to the leaf than that, it changes curvature at the tip. So I think it's a walnut, which in general is a much more likely find in this country.

The fruit is bitter because it isn't ripe, ready when gone hard like a nut!