Sounds crazy but jewelry is always a big hit with mom. Are the girl's ears pierced? (Many girls have them pierced before they're a year old.) How about small diamond stud earrings? Or a pretty gold baby chain that she then can pass on to her daughter someday?
The other thing I kept and passed onto my daughter was a small wooden table and four small chairs that my grandfather gave me when I was about 2 years old. My friends and I spent many hours playing at that table. You can order it via the Internet and have it shipped to the girl's house.