I claim the ornamental design for a gravesite border, as shown and described.
FIG. 1 is a perspective view of a gravesite border showing my new design, the gravesite border is drawn broken away for indeterminate length;
FIG. 2 is a top plan view thereof, the bottom plan view being a mirror image thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof; and,
FIG. 5 is a left-side elevational view thereof, the right-side elevational view being a mirror image thereof.
The broken lines showing a grave marker in FIG. 1 and a written sentiment in FIGS. 1 and 3 depict environmental matter and form no part of the claimed design. Portions of the design between the break lines form no part of the claimed design.