1911 Boston pin pinback button medal William Dorrety jeweler

Hi, new to CW, but I am posting this item that I just acquired and am trying to figure out what it is. The ring on this pin (button, badge, pinback?) appears to be added after the button was made but looks, to my untrained eye, to be from the period. I was told by the person I bought it from that it was from the 1911 Boston Marathon. I'm not sure what would indicate that. It was made by William C Dorrety Jewelers in Boston at the time, and they specialized in class and society pins, ribbon badges and jewels as you can see from the back of the pin. I haven't been able to find out much about them either. I can see it being a possible Red Sox item, Boston Marathon item, Boston University item. Is the 1911 a year, a locker number, not really sure what it could be. The seller said they asked about it here and that folks responded that it was Boston Marathon related. I searched here but couldn't find anything, but I am new to this site, so maybe I'm not searching correctly. Any help would be greatly appreciated. Thanks very much.
Gerard