The Ballad of Dennis Karjala contains the following two stanzas:

But when the nineteen extra years were nearly past and done,
those same proud barons then returned with cash to Washington.
"We want another twenty years, we hate the public domain.
And here's some cash that you can use to fund your next campaign."

and:

"Oh Congressmen, you are deceived! the lords of Hollywood
have made you to forget your oath to serve the common good."
"Hush you, Dennis Karjala, your egghead words are rash.
We'll listen to the film-lords, and to their ready cash."

Songs about the Mudcat's copyright troubles, such as "The Mudcat came back", (click here and scroll down) are of course indirectly about money.

T.