Searched: various folk songs and lyrics to old songs I know, but they're all out of context, so I don't know which would be a likely option.
My character is a teenage girl (a disproportionate dwarf, if that makes any difference) working at a carnival with her father. While she's walking around, she sings something to herself. What would be a song she would probably know and like? (With lyrics in the public domain.) Her father is Irish originally, but she's been exposed to all sorts of people from various regions at the carnival.
This is a children's story, so I need a song that would be appropriate for pre-teen readers.
(Edited to add title)