I think that the song could be "Mamma", because your first line seems the traslation of the first line of "Mamma" in Italian:
" Mamma, son tanto felice / perchè ritorno da te".
If this is the song you are looking for, it's not exactly a folk song, but it was a much loved song of the times of my mother. Here is a youtube video
http://www.youtube.com/watch?v=hrRIAWpIza8&feature=related
and the lyrics
http://www.italianissima.net/testi/mamma.htm
(sorry, I can't do blue clickies)
I hope it helped
ciao
paola