The ornamental design for a foodstamp, as shown and described.
FIG. 1 shows a top and side perspective view of a food stamp.
FIG. 2 shows a bottom and reverse side perspective view thereof.
FIG. 3 shows a top plan view thereof.
FIG. 4 shows a bottom plan view thereof.
FIG. 5 shows a side elevation view thereof.
FIG. 6 shows a reverse side elevation view thereof; and,
FIG. 7 shows a third side elevation view thereof offset 90 degrees from the views shown in FIGS. 5 and 6, the reverse side of the third side elevation view being a mirror image thereof.
The dotted lines are for illustration purposes only and form no part of the claimed design.