Well, I called USPS about my items.

They said: take it to the local post office. When I told them I had done that, and that they said they didn't want to deal with it, the woman on the other end of the line kind of verbally shrugged and said, "There's nothing we can do."

I feel worse about this than I probably should. It's most likely the USPS' fault - or more likely a careless/dishonest employee somewhere who either inadvertently broke into, or deliberately broke into (to take items they wanted) a box, and wound up repackaging the stuff in my box.

I've got to get rid of the feeling that it's my duty to find the owner of these items, because it isn't, and because I have no way to do it (there's no website apparently where these things can be posted). So short of going to every craigslist and the like sites in the nation and saying "hey is this your stuff?" I can't take care of it.