Here's a link to an article about a Gibson F-5 mandolin which has been used as a decoration near Kansas City for many years.

article

In case the linked article goes away, the story is that Victor and Lena Semisch of rural Butler County Kansas bought the mandolin in the 1930's. (or perhaps a few years before)

Victor played country music on it, and his daughter, who is now 80, thought 'Why can't he play something more up to date?'

The mandolin has been decorating the mantel since then, but recently someone wanted to play it. It was taken to a luthier in Lawrence who told them the amazing news about the beautiful tone and the $ value of the instrument.

Apparently it's still for sale if you have any spare change.