The barley charm is in the cellar of the bar. It requires flipping switches but I can't figure out the order.
In the centre of the maze beneath the bar is a note on the wall, it tells you the sequence of four color levers. Pull four levers in sequence and you'll be able to get into a room. At the up-left corner of the room you'll find another note on the wall telling you the sequence of five color levers. Just pull in the new sequence and you'll get the charm!