Restoration: go up a set of stairs, through a room, on a desk and there’s a golden chest
The Dark Within, during the Wizard boss fight: through the ceiling in an adjacent room, across the opening you entered in and around through a back corner and, presto, chest.
Forgotten Shores: through a cave with a small waterfall in front of it, chest is behind a big rock.
Forgotten Shores again: facing the broken pier, run down the shoreline underneath the pier until you reach a set of low rocks. Jump up the rocks and find the chest.
During the Devil’s Lair boss fight: go underneath the platform to the right and the chest will be waiting for you.