What is claimed is the ornamental design for a lawn mower, as shown and described.
FIG. 1 is a front perspective view of a lawn mower showing our new design;
FIG. 2 is a rear perspective view thereof;
FIG. 3 is a left side elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a front side elevational view thereof;
FIG. 6 is a rear side elevational view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
Any elements shown in dotted and/or dashed lines are provided for illustrative purposes only and form no part of the design claimed. Any surface shading is used solely to show the character or contour of the surfaces represented.