Well, I'm no parapsychologist, but if indeed you have a pesky ghost, it sounds like you have a poltergeist. Poltergeists are a kind of ghost that, more or less, just plays with people by moving stuff around. It sounds like you have a pesky but fun-loving 'geist, and that feather must have some meaning to the ghost. Without intensive investigation, no one can give you a more detailed description. Unless the ghost gets violent, it's just best to leave well enough alone, and tolerate his or her antics.
-------
Vote for REAL change.