Mama Corleone is the hearty, nurturing bosom of this great family; often seen but rarely heard.  

To her right is one of Don Vito's Capos, Tessio - and, no, you are not hallucinating that really is Abe Vigoda.

Tessio holds an orange, one of the first of many references to citrus fruits in The Godfather that sends over-analyzing film scholars into a tizzy.