I send Christmas, Teacher appreciation week and end of year gifts.
Christmas and year end gifts tend to be more of a personal gift for the teacher. Teacher appreciation week, I tend to send in things the teacher needs for the classroom, since this is what the PTA has asked us to do.
Also for teacher appreciation week, the PTA has a sign up for potluck dinner for the week. Each day has a theme (taco day, soup and salad etc), so I also contribute to that.
The teachers don't mind getting supplies for their classroom during teacher appreciation week since the schools are strapped for supplies.