CHICAGO — How much do you really know about civil rights activist Fannie Lou Hamer? In these pandemic years, her story has been told on the Goodman Theatre stage and in Chicago parks by way of Chicago-born playwright Cheryl L. West and historian Keisha Blain, a fellow at the Carr Center for Human Rights Policy at Harvard University, who authored the book “Until I Am Free: Fannie Lou Hamer’s Enduring Message to America.” Both writers share the story of Hamer, who died in 1977 and didn’t come to activism until her 40s, centering her voice on voting and women’s rights. The Mississippi sharecroppe…