Missing pieces

As I was opening my car door tonight, I happened to look at some dead leaves caught in the hinge of the door. In amongst the dead leaves I found this - a couple of jigsaw pieces tied up with a tag, asking me to go to the quad in the university on the 16th December. I guess someone had left these on some of the cars in the uni car park before Christmas, and unfortunately, mine had dropped down inside the door without me noticing. What a shame. I would've loved to help make the jigsaw.