I'm doing a soundtrack project for The Great Gatsby and I need a song that relates to Myrtle Wilson on the theme of wealth.
Could I suggest the song "Gold Digger" by Kanye West, featuring Jamie Foxx? (However, I also suggest finding an edited version of the song that does not include offensive language.) Obviously, Myrtle benefits financially from her relationship with Tom Buchanan just as the titular "gold digger" in this song. The introduction says, "She take my money [...] / Yeah she's a triflin' friend indeed./ Oh, she's a gold digger, way over town / That digs on me." Such a description fits Myrtle Wilson to a T: she takes Tom's money (for her dog, an apartment, clothing, liquor), and she is "triflin'" as she would likely not care so much about him were it not for his money and situation. Further, she is literally from "over [a] town" since she's from the Valley of Ashes, and she definitely "digs on" Tom.
Further, similarly to the woman in the song's hook, Myrtle "ain't messing with no broke" men because she is only interested in being with someone who can take her away from her sad-sack husband and his dusty auto garage. It is money she's after, not love or companionship, and this makes Tom pretty perfect because he can offer her money and nothing else.
There are several lines in the verses as well that you could relate to Myrtle's hunger for wealth and appreciation for material goods.