Barb, Here is an early marriage in Branch County, MI. for EARL surname. This might be the son Frank you mentioned:
Earl, Frank L., 20, b Bronson, of Bronson, farmer,m Mina Smith, 22, b Jonesville [Hillsdale Co.], MI., of Bronson on 23 Dec 1874, at Bronson, by Edward A. Gay (Clergy), witnessed by Frank E. Roberts and Edna Smith, both of Bronson. Record # 5667.