FIG. 1 is an exploded view of a tray insert showing our new design along with a gift card and a tray; FIG. 2 is a perspective view thereof; FIG. 3 is a front view of the tray insert, the rear view being a mirror image thereof; FIG. 4 is a side view thereof, the other side being a mirror image thereof; FIG. 5 is a top view thereof; and, FIG. 6 is a bottom view thereof. The broken lines shown are for illustrative purposes only and form no part of the claimed design.