According to the DOELP (s. v. Vila Verde), it is common in northern Portugal and Galicia as a designation suggested by the greenness of the fields; it also favours connotations of fertility and productivity.

Cited bibliography: 

DOELP = Machado, José Pedro. Dicionário onomástico etimológico da língua portuguesa. Lisboa: Livros Horizonte, 2003, 3ª ed.