What is supposed to ensue when finding a coin in your plum pudding?

A Touch of Silver
You'll no doubt be familiar with the act of adding silver coins into Christmas pudding. This tradition came from the notion that whoever finds the coin in their pudding serve can keep the coin, AND has the added bonus of "good luck" for the new year ahead. Over time, what began with a single coin evolved to include several coins to share the luck around.
Variations on the currency of Christmas Pudding
Many variations of the silver coin token have been baked into Christmas puddings over the years, including:

• Silver crown: the person who finds the token in their serve of pudding was said to be king or queen for that night
  
• Horseshoe or Wishbone: it is believed the finder will have good luck for the coming year
  
• Silver thimble: thrift - the finder will have good fortune and wealth for the new year
  
• Anchor charm: safety and protection for the finder
  
• A ring: the finder will get married in the next year