King cake trinket
The traditional trinket in the cake is a bean, still seen in some European traditions but rare in U.S. king cakes. It is echoed, however, in some krewes' use of a gilded bean trinket.
In the US Gulf Coast since the 1950s, the most common trinket has been a small plastic baby doll. Many people say this represents the baby Jesus, tied in to the connection with Epiphany. Many people attach no particular religious significance to the cake or trinket. The "baby in the king cake" was said to have become common after a New Orleans area bakery chain got a large shipment of such plastic baby dolls from Hong Kong very cheaply in the 1950s, and some people say there is little further significance to the baby, but earlier ceramic baby dolls as trinkets are documented in New Orleans back to the 1930s. Another local opinion passed down through families is the baby represents the re-birth of Father time for the new year.
A trinket representing a king wearing a crown is the next most common design of trinket. Trinkets in the form of other figures have also been seen historically, and starting in the 1990's again became more common in the more expensive "gourmet" varieties of king cake. The common plastic baby of today is usually colored pink, brown, white or gold. Due to the choking hazard posed by small trinkets, some bakeries opt to include the doll separately from the pastry. The baby dolls are most often found separately in cakes from stores not native to New Orleans such as Sav-A-Center, whereas local bakeries are more likely to sell cakes with dolls already inside. Usually when kingcakes are ordered to be shipped out of New Orleans the cake and trinket are packaged separately so that the tiny doll will not pose a choking threat to kingcake novices.
Source: King cake - Wikipedia, the free encyclopedia


