We have a family heirloom (I guess), it's a signed photo of Abraham Lincoln, small, like wallet sized, I really need an expert response or someone that knows how to get a hold of an expert to get an estimate on value, I know way back we have a relative that served with Lincoln in the war, and was friends with him, but how do I get this cerified, I doubt a collector would just "take my word for it". Thanks...

The public library has books on collectible photos and autographs plus prices. Also, ask the reference librarian to give you several names and phone numbers of experts whom you can contact and find out what their requirements are for authenticating such a photo.

I noticed you live in Chicago, I don't know if the Austin, Tx librarys are quite as extensive, but I'll look into it anyhow, thanks :-)

Other answers are still welcome !