The ornamental design for a foodstoragecontainerbase, as shown and described.
FIG. 1 is a front perspective view of a food storage container base, showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is left side view thereof;
FIG. 5 is a right side view thereof;
FIG. 6 is a top view thereof;
FIG. 7 is a bottom view thereof; and,
FIG. 8 is an exploded front perspective view thereof, with an unclaimed lid.
The broken lines depict portions of the food storage container base that form no part of the claimed design. The dash-dot broken lines of FIG. 8 represent the direction of assembly and form no part of the claimed design.