As a previous teacher of over 10 years, I wanted to just weigh in here. As for food, unless you know exactly what she likes or is/isn't allergic to skip the food. Honestly, most food gifts are either thrown away by the days end or given away to the "staff lounge". Same with coffee stuff. Each year I ended up with 3-4 large baskets of coffees and the key was I am not a coffee drinker and neither is my hubby. so, it was always given away by the days end so as not to waste it. As with Bath soaps, bath beads, and lotions, again unless you know of a specific fragrance she prefers don't go this route. I can't tell you how many bottles of fragrance I have tossed out over the years because I couldn't swap it or return it for something I liked the smell of day in and day out. Be sure if you go with bath stuff to make sure she doesn't have allergies. One of my coworkers is allergic to certain oils and ended up having to throw out or give away bath products.
the one piece of advice I will throw out is make sure your teacher is not from a religion that doesn't accept gifts. There are some people who are not allowed to accept them per religious beliefs. It can be a very uneasy situation for this person to have to refuse your gift and risk hurting your feelings OR to have them give it away to someone else so as not to offend saying something to you.
The best gifts I ever got were gift cards to movies, places to eat, or various other stores. That way I got to choose something I liked or preferred.
