The Fête des Rois (or Festival of Kings) takes place on the 12th day after Christmas and is known as the Epiphany. In France the tradition is marked by a dessert known as the Galette des Rois or King's Cake which is sold with a paper crown.
Pastry shops throughout France bake thin frangipane pies that contain a bean (known as the fève). After dinner the galette is cut into slices. The youngest member of the family is the one who decides who gets which slice. The person who has the "fève" in his/her slice is crowned King or Queen respectively. In Provence a brioche version with candied fruit are also baked. I tend to favour the traditional flaky crust version.