The black snake with a yellow belly is called a "Southern Ring-necked Snake," or just "Ring-necked Snake." These snakes have a black, or dark grey back, with smooth scales and a yellow or bright orange belly. The belly often has a row of black spots.
As its name suggests, the Ring-Necked Snake, or "Diadophis punctatus punctatus," also has a ring around its neck; this ring is also yellow or orange. The ring-necked snake is fairly small in comparison to other black snakes, seldom growing longer than 12 inches. They live mostly in the eastern United States and can often be found in suburban neighborhoods.