The ornamental design for a remindercoin, as shown and described.
FIG. 1 is a front view of a reminder coin showing my new design;
FIG. 2 is a right side view of the reminder coin, a left side view being identical;
FIG. 3 is a top view of the reminder coin, a bottom view being identical;
FIG. 4 is a top front side perspective view of the reminder coin; and,
FIG. 5 is a front view of an embodiment of the reminder coin in use.
The rear view is not claimed as part of the design. The dashed broken lines in FIGS. 1, 4, and 5 are illustrative of portions of the reminder coin which are unclaimed and form no part of the claimed design. The dash dot dash broken lines in FIG. 5 are illustrative of environmental structure forming no part of the claimed design.