One of my favorite writer stories has to do with an old-time pulp writer and historian of note named Manly Wade Wellman. Wellman was known for, among many other works, the "Silver John" series (Who Fears the Devil is one Silver John title), on which into a film and a Civil War history that was nominated for the Pulitzer Prize (Rebel Boast: First at Bethel, Last at Appomattox).
Wellman was asked to write a story for an issue of the Superman comic book. He duly wrote and turned in the story, and it was published. After waiting a polite amount of time, Wellman asked about his payment. He was told that he wasn't being paid, and that he couldn't prove that he wrote the story. (When published, the story had no byline.)
The matter ended up in court, where Wellman proved that he'd written the story by showing that if you wrote down the first letter of each sentence in the speech balloons over characters' heads for several pages, you would spell out his name. He had, of course, set up the dialogue that way. He was paid.