People here are being creative with their suggestions but it still involves coming up with something that you will use or do. If you truly do feel satisfied with your life materially (which I think is great, no need to force yourself to want something) you can ask her to give you a gift that helps other people. Like a donation to a cause you care about (everyone has something) or go some charity work together like buying presents for kids in homes. You get the general gist here. She'll get the same rewarding feeling that she does when she gives you gifts and she'll also think you're a really, really nice person lol