Abraham Lincoln, of course, ran for President of the United States in 1860. His running mate for Vice President was Hannibal Hamlin, a politician from the State of Maine. This was a campaign button for that election. Lincoln won.
A 'ferrotype' is a photograph printed on metal. The pictures fade somewhat, but are still easily recognizable.
The brass-framed ferrotype in our picture comes from Stack's Bowers where it sold for $425 US dollars in a 2005 auction. These are valuable pieces when they are in good condition. As long as your ferrotype had historic interest and is in decent shape, you can expect values starting at $200 and going up from there.
Dennism describes his item as 'mirror-like surfaces' which means it is in good condition. Not only that, the $425 price was back in 2005 and the value has certainly gone up since then.