Dolly Parton and Porter Wagoner were not happy with each other after they stopped working together. Parton wasn't thrilled ...

Dolly Parton said Porter Wagoner didn't discover her. He believed he still played an important role in her career success.

In a PEOPLE exclusive clip from his film Country Music, the 75-year-old speaks ... and long-term working relationship with Porter Wagoner in 1974, after working together for seven years.

Emmylou Harris' song, "To Daddy," was never supposed to be hers, though, thanks to Dolly Parton's rebellious ways, it was and always will be.

Dolly Parton is arguably the most important female singer ... in country music history. Beginning her career as a songwriter in Nashville just after graduating high school, she joined Porter ...