That's not a daisy, it's a marguerite. A daisy is smaller. This is a daisy:
http://fr.wikipedia.org/wiki/P%C3%A2queretteThe French word for daisy is "pâquerette".
They are from the same family. And sometimes a marguerite is called daisy marguerite in English. But in French and
German there's a distinction. A marguerite is bigger and a daisy is small. They are from the same family but not the same flower even though they look similar. That's why
Daisy never made sense to me as a nickname for
Marguerite ;) I think it's fine for someone else I just wouldn't do it.