For decades, this Mississippi bluesman was mostly unknown

RL Burnside on the cover of his 1998 album, Come On In.  Burnside played music nearly his entire life, but didn't record until his 40s, and didn't find widespread acclaim until the 1990s, when he was already in his 60s.   

Can We Agree that Rock Steady is Aretha's Best Song?

The original cover of the album Young, Gifted and Black, by Aretha Franklin.

When The Levee Breaks

Memphis Minnie and Kansas Joe McCoy.  Memphis Minnie wrote the original version of "When the Levee Breaks," and recorded it in 1929 with her second husband and musical partner Kansas Joe.