What gift can you give your mentor ?

I have a mentor at my workplace and she would now be moving on to another job.

I started working at this place about 5 months ago and she has really been helping me come to terms with my job, explaining me everything and guiding me throughout.

I almost got into trouble at this job when I missed a few deadlines, but she always stood by me and took the blame upon herself just to defend me.

Before she leaves, I want to gift her something for all that she has done for me.

What should I gift her ? Any ideas ?