The King of Swineherd's crown is a trophy added by the Hearts of Stone expansion for The Witcher 3: Wild Hunt. This trophy is awarded to the King of the Swineherds, whom you may become by winning the pig herding contest at the wedding during the quest Dead Man's Party. Note that you have to win the contest fairly (can't use Axii). It can be placed in the trophy slot in the inventory panel to provide 15% bonus gold (the highest bonus gold percentage for trophies). Unlike most other trophies, the King of Swineherd's crown is not a monster part, but rather a large stuffed toy resembling a pig.