My most meaningful souvenirs are all my pictures from Italy. Once I returned home I printed off all the pictures my friends and I took while in Italy and I put them in to a photo album.
During the first month or two of being home I was really missing Italy, more than I could have ever anticipated. Having all those pictures in one place that I could look at whenever I wanted was extremely helpful. When I looked at the pictures it was almost as if just for the second I was back in Italy again.