I would start with MLK, collected essays, no one writes about protest more eloquently.

A Peoples History of the United States by Howard Zinn gives a great broad overview.

Death in the Haymarket by James Green is a great history of the first decades of the labor movement.

Doris Kearns Goodwin's Leadership in Turbulent Times goes in depth on LBJ and the civil rights movement.

On the Duty of Civil Disobedience by Henry David Thoreau for the classic philosopher's take.

We've Got People by Ryan Grim details the successes and failures of the movement in the last decade.