While not necessarily "dumpster diving" I have snuck out late at night to snag the neighbors' almost new recliner chair that perfectly matched our cabin up north. I had to drag DH outside to help me get it into the garage, he was sooo embarrassed.
Of course, now we can never invite those particular neighbors' up to the cabin for the week-end LOL
Oh, and I have found quite a few good items for our Halloween Haunt that we have. Things such as old dining chairs, gilt edged mirrors, and my favorite was a really old looking picture with a cool frame. Of course these things are for Halloween , so the older they look the better. Just grabbing these from the end of people's driveways on garbage day though, not actually dumpster diving.