The ornamental design for a sprinkler head grass trimmer, as shown.
FIG. 1 is a top perspective view of the sprinkler head grass trimmer. The
broken line structures are for illustrative purposes only and form no
part of my design.
FIG. 2 is a bottom perspective view thereof.
FIG. 3 is a top plan view thereof.
FIG. 4 is a side elevational view thereof.
FIG. 5 is a side elevational view rotated approximately 90° with
respect to FIG. 4.