Wine or booze.
I remember when I was 8 or something, my mom sent a bottle of scotch or something like that with me to school for my teacher. I was so embarrassed. But, boy, did the teacher just love it.
Another thought is, find out which teachers your child's teacher is friendly with, and ask them. I presumed that my son's teacher this year is Muslim and therefore doesn't drink, so I asked one of his friends for confirmation b/c I didn't want to give him wine if that was the case. And it was. So, I got him movie tickets instead.