What is a good song that represents To Kill a Mockingbird?
When we think of songs that "represent" things, there are a few things to consider:
1. Sound - does the sound of the song match the feeling of the novel? If I picked a heavy metal song to represent a Curious George book, that would say something about the feeling I get from the book.
2. Lyrical Relationship - do the lyrics have any special tie to the content of the book? This isn't always necessary, especially with music that isn't lyrical, but it is a good consideration.
3. Message - what overall message does the song send?
4. Avoiding "On the Nose" Choices - this is hard. It can be tempting to choose a song that very, very closely matches the theme and feeling of the book. This is a mistake because it doesn't allow any imagination in the listener/reader. An example would be choosing a song about a sinking ship to represent the Titanic. When the relationship between the pieces (sinking ships) is already established, the reader/listener doesn't get the chance to make those connections for herself.
Given all of this, I recommend the song "Helicopter" by the band Branches to represent To Kill a Mockingbird.