The ornamental design for a baseballfieldplanter, as shown and described.
FIG. 1 is a top and side perspective view of a baseball field planter showing my new design;
FIG. 2 is a left side elevation view thereof;
FIG. 3 is a right side elevational view thereof;
FIG. 4 is a front side elevational view;
FIG. 5 is a back side elevational view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view.
The broken lines in FIG. 1 showing grass growing from the baseball field planter are used for illustrative purposes only and from no part of the claimed design.