The ornamental design for a cover for foodcontainers, as shown and described.
FIG. 1 is a perspective view of an embodiment of a cover for food containers showing my new design, the thick broken lines on the cover indicating perforations forming a tab and the thin broken lines showing a container depicting environment only and forming no part of the claimed design;
FIG. 2 shows a container thereof filled with a product and an inserted utensil, the broken lines forming no part of the claimed design;
FIG. 3 is a top plan view of FIG. 1;
FIG. 4 is a perspective view of FIG. 1 showing a tab portion opening; and,
FIG. 5 is a perspective view of FIG. 1 showing the tab portion open, the broken lines showing an inserted utensil depicting environment only and forming no part of the claimed design.