Found in my yard, outside of Philadelphia in PA. Not sure if it's worth anything, due to there not being a tin type photo left after years in the ground. I also don't know if it would have been a picture of Lincoln or McClellan. Really cool find for me regardless!!!
Hard for me to see it but a lot of the fun of this hobby is doing some research try googling your pin or even eBay see what you find or post it in the what is it forum, I think you may have found something really cool