Great looking photo. No idea as to its value. Others here will know much more about items from that era than I do. I googled "mbbc maryland baseball". Came up with links to a couple of pages related to early Baltimore baseball history and references to a "Maryland Base Ball Convention" and an Antietam club in Hagerstown. Have a look. Might shed a little bit of light on your photo.
http://baseballhistoryblog.com/categ...istory/page/2/
http://baseballhistoryblog.com/2006/...eball-part-10/
There is a link to the website's author Brian McKenna (click "About Me"). If the scholars at Net54 hit a dead end you might contact him.