Michelle Obama, Bill Clinton, Oprah, and actress Cicely Tyson are expected to pay tribute to poet and civil rights champion Maya Angelou at a private memorial service on Saturday at North Carolina's Wake Forest University, where Angelou was a professor of American Studies since 1982. Singers Lee Ann Womack and BeBe Winans will perform. Angelou, a Presidential Medal of Freedom recipient, died at her home on May 28 at the age of 86.