The "brass" cents are usually just from being in the copper plating bath that has been diluted with zinc if I'm not mistaken. I don't believe they have much, if any, added value. I see these fairly often in my roll searches and I don't keep them unless they are spotless. Yours is far from that and I wouldn't keep it if I came across it.
I have a question about these as well. I find the bright yellow ones that some call "Yellow jackets" which they say are brass. As furryfrog02 said I think he is right. I believe most of these that are thought to be "brass" are just toning. My question would be if they have become truly brass, would they lose their color if dunked in cleaner or if one used brasso cleaner? As I found quite a few very neat looking yellow ones I decided to experiment on two of them with jewelry cleaner. They both went back to a nice copper look losing their beautiful yellow color (doh). So if any are out there that can answer if it was truly brass should it change, I would appreciate it Anyways this why I think most of these are just toning, but I could be wrong.
BTW have you checked the cent that is yellow on the right for Memorial Bay extra columns? It almost appears that there may be, but the photo is far off and could be lighting.
