What does Birdie want Cal to get from her house in Little Foxes? Why?

Birdie sends Cal to pick up some music from her house; she's hoping that William Marshall will like it.
Cal works in the Giddens' household as a servant. One night, before dinner, Birdie takes Cal aside and asks him to go to her home, pick up some music, and return to the dinner party. William is visiting from Chicago and Birdie thinks the music will impress him.
William is there to close the deal on a cotton mill that Birdie's family is hoping will bring them more fortune. Before Cal can leave, however, Oscar steps in and stops him from running the errand. He tells Cal that he doesn't need to get the music. Then Oscar tells Birdie that it's unnecessary and she shouldn't be boring William. This mirrors Oscar's attitude toward Birdie throughout the play.