FOR METRO. Boston, MA 5/20/2012 A student decorated her hat for the commencement ceremony. The Boston University commencement takes place on Nickerson Field in Boston, MA on Sunday, May 20, 2012. (Yoon S. Byun/Globe Staff) Section: METRO Slug: 21bugraduation Reporter: Mark Arsenault LOID: 5.0.1298659016