When I was a teacher, the generous parents spoiled me and my co-teachers with candy, bath stuff and candles at the holidays. We especially liked gift cards (of course) but some of the my favorite gifts were holiday decorations.
One of the best was this ornament. A mom used a paint pen to write the year and all of our students' names on a plain glass ball. The next year, I made one for myself and my co-teachers, and this year I replicated the idea for my son's preschool teachers. It's easy and inexpensive: A package of four plain glass ornaments cost about six dollars at Walmart this year, and a pack of paint pens was about ten dollars. The same idea could work for other holidays: A wooden heart on Valentine's Day, a ceramic egg on Easter, a small pumpkin at Halloween, etc.
Just, um... be careful, and maybe buy an extra or two. You know, in case you, I don't know, misspell a name or drop one on the floor. Not that I know from experience or anything. Just saying.