It's one of those songs which keeps cropping up everywhere. Numerous versions have been collected from Spanish and Sephardic Jewish traditions ("Romance de la gentil dama y el rústico pastor"; Menéndez Pidal, R. & Torner, E. (1944): "Flor Nueva de Romances Viejos"), a rare example in Guernsey-French (text in the final chapter of Marie de Garis' "Folklore of Guernsey"), and I am told there are also versions from Brittany. In each instance it's a dialogue between a lady of breeding who fancies a bit of rough, trying to persuade a a peasant - usually a shepherd - to come home with her. In at least one Spanish version she actually fails, even though she draws attention to her nipple erection ("Mis teticas agudicas quieren el brial romper") amongst other attractions.