I claim the ornamental design for a pill box, as shown and described.
FIG. 1 is a perspective view of a pill box, showing my new design;
FIG. 2 is a perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a right-side elevational view thereof, the left-side elevational view being a mirror image thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines showing a pills and a necklace in FIG. 1 and a text logo in FIG. 4 depict environmental matter and form no part of the claimed design.