"Dollar Bills" is the first song ever written by Lady Gaga when she was 6.
My dad was listening to what I now know was Pink Floyd's "Money,” and understanding only the sounds of the cash register in the intro, I wrote a song called "Dollar Bills” on my Mickey Mouse staff paper. The musical notation was of high quality in comparison to the lyrics on the page—none of which were actually spelled correctly. I've always had some difficulty saying what I really mean with just words.
Gaga later mentioned the song again on 60 Minutes with Anderson Cooper and briefly showed the musical composition of the song. From what could be seen, it appears to be in the key of A major.