When Will Zimmerman was under the influence of a psych worm in late 2010, he saw himself as a heart surgeon, and believed that it would have made his mother proud. In this dream world, Mary Anne Zimmerman is still alive. He intended to call her at some point.
Name: Her character is listed a Will's Mom on IMDb. Her character's full name, year of birth, and year of death were revealed on her tombstone in the fourth season Episode 4x06 - "Homecoming".