Tractor footprint art. Get their little footprint onto some white scrapbook paper. Then print off a tractor image online, you might need to blow it up to fit the size of the footprint. Cut out the tractor pieces and trace around footprint with a pencil and paint. Could be done with anything I bet. The link on this is the tractor I used to trace
I am repinning this site for you guys that still receive tooth fairy visits :) Incredible ideas here!! And one of my own: I used to use extra fine glitter (fairy dust) from Michaels and sprinkled it around on the nightstand with little "footprints" (from my pinky finger). The looks on the kids faces...priceless!! Sean and Joshua still remember it, all these years later!