That's really sweet...
The box idea is great. I had a college boyfriend who gave me a decorative box with a rock inside from the beach. I still have both.
And if you're not the sentimental type:
One Valentines Day my ex husband took my car and got it cleaned- inside and out, and detailed. That was the best gift I ever got. With everything else I was juggling, the car was always trashed. I hated driving it that way but didnt have the time to clean it up. It was the perfect gift.
It's like, "How much more black could this be?", and the answer is none. None more black.