I claim the ornamental design for a pillow, as shown and described.
FIG. 1 is a top view showing my new design for a pillow;
FIG. 2 is a first side view showing the design of FIG. 1;
FIG. 3 is a second side view showing the design of FIG. 1;
FIG. 4 is a third side view showing the design of FIG. 1;
FIG. 5 is a fourth side view showing the design of FIG. 1;
FIG. 6 is a bottom view showing the design of FIG. 1;
FIG. 7 is a perspective view showing the design of FIG. 1; and,
FIG. 8 is a second perspective view showing the design of FIG. 1.
In FIGS. 2-8, the broken lines depicting the underside of the pillow form no part of the claimed design. In FIGS. 1-5 and 7-8, the dashed lines superimposed onto the solid lines on the face of the pillow represent stitching that forms a part of the claimed design.