- Locker shelves. Boy I wish I knew about these when I started high school.
- Disposable camera, for all of the fun times she'll have.
- Those plastic/stretchy book covers. Man those are cool.
- You could make her like a "locker emergency kit", maybe with a little mirror, some bandaids, some hair elastics, a small compact, mints...
- A photo album with pictures of her from elementary school so she never forgets where she came from
Just a few ideas