According to :
On Thu, 08 Nov 2007 08:09:40 -0800, GeekChick
wrote:

My Mom found a key today that my Dad was hiding behind a picture. He
died many years back, so I have no idea what it goes to and I was
hoping that someone could help me. I have the picture posted at my
website:

www.geekbyphone.com/key.html

Looks very much like a key to a bathroom or other interior door. He
probably kept it here so you wouldn't take it when you were a kid and
locked yourself in the bathroom or your bedroom occasionally.

Yeah, looks _very_ much like the "key" people use to unlatch
interior door locks on bathrooms for when the door is accidentally
locked from the wrong side, or the kid locks themselves in. These
days people usually use screwdrivers or roasting skewers.

[Or at least, I do ;-)]

The other thing it's location suggests is that it might be
a key for something they didn't want you getting into - like
a very old/primitive/not-very-secure lock on a gun or money
box or something like that.
--
Chris Lewis,

Age and Treachery will Triumph over Youth and Skill
It's not just anyone who gets a Starship Cruiser class named after them.