They are all over the Wilds.
You must find the Rob-goblin junk piles and receive the key for the treasure chest found in the black spore grave yard.
Anywhere that you see one
Anywhere, the locations are randomized
its in the Robgoblin junk pile but its kind of rare so look out!
there in robgoblin junk piles
Near the River in the Sanctuary is a great place to look, or in Most of the Southern Wilds & Greenwood.
The piles of junk in Knotwood Forest contain idol pieces, or a hole that leads you out of the cave.
The last idol is found in one of two piles of junk bones. It is on the way to Digadig village.
The answer is know one knows its in random spots.
you have to find certain coins to get them
From key collection.Keys can be found in robgoblin junk pile rare collection.When you finish go to the chest that mach with the key you get from collection and open it....:D
It's always in different piles.