Sometimes obtained after Goblin Digger buries item - search the location you see the Goblin Digger buries something. If you're close, you will see "You feel there's something nearby." Keep digging in the immediate area, trying to get as close as possible to the actual spot the Goblin made the action to bury the item.
|● = Requires Burrow ● = Requires Egg Helm|
● = Requires Bore ● = Obtainable only at Night