I am a teacher and the best gift/thank you I ever got was a letter from a parent. It expressed her initial concerns and how they passed and what a different I had made in her son's life. I will treasure it forever. It reminds me why I started teaching in the first place and when I am done staying home with my babies I'll read it to remind me why I want to return. I think a heartfelt note means more than chocolates, etc.