Listen to the Celtic Harp
The Celtic harp (also called an Irish harp, lever harp, or folk harp) differs from an orchestral harp in two main aspects. The orchestral harp is larger and uses foot pedals to change keys. The Celtic harp uses levers attached to the frame to change keys and are smaller, sometimes small enough to hold on the lap, making them easier to transport. The sounds of Celtic harps will vary, depending on their size and the type of string they use.
It is used for the Shire music, especially the Hobbit/Rural Setting of the Shire Theme. A good spot to listen is when Bilbo tells Gandalf (over tea) that he thinks Frodo might come with him but he's still in love with the Shire.
via ethnic and exotic instruments of LOTR