@timdownie found this on the wikipeadia - Tooth Fairy. Many a refractory child will allow a loose tooth to be removed if he knows about the Tooth Fairy. If he takes his little tooth and puts it under the pillow when he goes to bed the Tooth Fairy will come in the night and take it away, and in its place will leave some little gift. It is a nice plan for mothers to visit the 5-cent counter and lay in a supply of articles to be used on such occasions.
— Lillian Brown, Tooth Fairy,