What gift to give depends on your mentality and your own ideas. If you still like her and want to get back together with her, you can give her a slightly more grand gift. For example, you can frame the sweet photo you two once took together in an exquisite photo frame. Then, put it in an exquisite gift box. Attach a card in which you can express your meaning in a tactful way, but don't be too direct. Finally, stick a red rose on the outside of the box.
Haha, this gift is not bad. If you are afraid that you can't write it well or make it well, you can find a special gift website or gift shop and ask a special staff to help you make it.
If you don't mean to get back together, you are just friends. Then you can give her the gift according to the standard of treating ordinary friends! Most girls like delicate objects, such as music boxes, wind chimes, crystal bracelets, necklaces, hairpins, etc., which are all good choices.