In Baldur's Gate, if you met Coran and accepted his side quest, you can hunt down one wyvern and sell its head for 2,000 to Kelddath in Temple. Other heads can be sold to Officer Vai for 1,000 (not in BG:EE), or at the few stores that will buy this item. Thalantyr the Conjurer at High Hedge and the bartender in Feldepost's Inn will each buy a first lot of heads for 500 each, and further heads for 200 gp.
In Baldur's Gate II it can be sold to stores, but there is nobody who collects wyvern heads or uses it to make something. Wyverns which are summoned by the 6th level wizard spell Wyvern Call will drop this item if they are slain.
It weighs 30 pounds.
|“||The severed head of a wyvern is both a fearsome and a reassuring sight. Gruesome as its fanged maw and blazing eyes may be, there is consolation in the knowledge that they can be conquered by mere and lowly mortals.||”|