In Christian tradition, Epiphany, or Kings Day, commemorates the visit of three kings, Melchior, Caspar and Balthazar came to be presents to the Child Jesus of myrrh, frankincense and gold. To find their way to the manger, the Magi followed a star brighter than all others. The star that guided them is called the evening star. In 1801, it was decided that the date of the Epiphany (which means 'appearance') would be January 6.
Today, the tradition is for the 'Day of the Kings', we share a cake called galette. In southern and western France, we share a cake shaped like a crown. In this cake or this ring is hidden a bean, usually porcelain. Custom dictates that the youngest of the family crawls under the table to help with distribution and decide who gets which part. Thus, nobody can cheat. Whoever eats the part containing the bean is declared king (or queen). We put a crown on the head of the king who must choose his queen (or otherwise).