Your grandfather's name (Giovanni) sounds familiar from some past research of mine.......... Do you know if he had a relative named Giacamo (James)? Giacomo's father was Lorenzo Castagnoli. His mother was Maria Pallia. It looks like James came to the USA via Ellis Island, with information found at geneology.com saying Dec. 26, 1893, port of Embarkation: Harve. It appears that Giacomo possibly returned to Italy to bring Irene back to the U.S. Giacomo spent some time in Illinois (maybe 36 plus years) before moving to Vallejo, CA.
Does any of these names, locations or dates ring a bell?