Subdued means "quiet and rather reflexive" or "soft and restrained."City: Wichita, Kansas is subdued because I've lived there, and it's a lot calmer than most cities, and the farmland is quiet and peaceful.
Song: I picked "Hallelujah" because even though the song is sad, it's still quiet.
http://www.youtube.com/watch?v=y8AWFf7EAc4 
Character: Ben from "Lost" is subdued because he manages to appear relatively emotionless in all situations. He could be about to get shot or about to shot someone, and always has the same calm look.
Clothing
Turtleneck sweaters are subdued because they are low key and suggest a calm nature of the wearer. (I don't know why, but it keeps deleting my turtleneck pictures)
Bread is calming to an upset stomach.
The sublimity of oceans and the beauty of nature is often calming and settling for people.
