I love getting cards and little handmade gifts that indicate a child cared. I also like gift cards! I work at a private school, and it's customary to give teachers lavish gifts. Since my birthday is around teacher's day, I often get so many that I'm blushing.
The best gifts that I have ever been given are the heart felt notes and letters written by students in which they actually identify something specific I've done to help them. As teachers, we sometimes work long days with little validation, and moments like that reinforce the reason we do this.
Teachers always cherish those handwritten, sincere notes of appreciation from students. Even after they retire, teachers come across these messages of the heart from youth and a tear sneaks out anew.
I never expect much, so I agree that anything from the heart is a blessing. I love finding a hand-written note of appreciation placed on my desk after class or in my school mailbox when I arrive. Never ceases to bring me to tears, and I am humbled by the gesture. I once got a long-stemmed chocolate rose, and several times I've gotten one simple flower. Such a small thing, really, but I was quite moved. For me, though, nothing is better than the words. Thanks for asking!
I'm going to post the first answer as this question has been up for a while... as a teacher AND a mother, I get this question a lot - from parents of students - or parents who know I'm a teacher but I don't necessarily teach their kids. Everyone wants to know, "What do teacher's really appreciate when it comes to gifts?"
To be honest (and not to sound tacky) - teachers love gift certificates. The fact is, we do this job because we love it, not because we get paid a lot - and any time someone gives us a pass to go on a personal shopping spree (even if that is just a trip to Starbucks for one day) - we are going to love it. I think a safe gift card is Barnes and Noble. Books or coffee - you pretty much cover all the bases.
If you wish to do something more sentimental - I can also speak for many when I say that a genuine, heart-felt, thank you - ALWAYS blesses us. We work in a job with that comes with very few immediate emotional rewards - truly, and when students take a minute to sit down and say thank you - and include a couple of specifics - it might even be better than a gift that money can buy.