The ornamental design for a spoon, as shown and described.
FIG. 1 is a perspective view of a spoon showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a right side elevational view thereof;
FIG. 5 is a rear elevational view thereof;
FIG. 6 is a bottom plan view thereof; and,
FIG. 7 is a left side elevational view thereof.
The images filed as informal drawings illustrate a ZESPRI and FAN logo in FIGS. 1, 2 and 6 and particular colors in all figures. These details do not constitute an integral part of the disclosure and the claimed design.