The ornamental design for a cushion, as shown and described.
FIG. 1 is a top view of a cushion according to the present invention;
FIG. 2 is a front view of the cushion of the FIG. 1;
FIG. 3 is a rear view of the cushion of FIG. 1;
FIG. 4 is a first side view of the cushion of FIG. 1;
FIG. 5 is a second side view of the cushion of FIG. 1, opposite the first
side shown in FIG. 4;
FIG. 6 is a bottom view of the cushion of FIG. 1;
FIG. 7 is a top view of a cushion showing a second embodiment of my new
design, the sole difference from the first embodiment resides in the
presence of an opening; and,