The ornamental design for a plate, as shown and described.
FIG. 1 is a top view of the plate of the invention;
FIG. 2 shows a detail of FIG. 1; and,
FIG. 3 is a side view thereof, the plate being symmetrical such that all side views are identical.
The background surfaces on which the claimed plate is shown to be resting, as well as the bottom surface of the plate, are not part of the claimed design.