I will give you a few ideas, though. Since teachers don't make much of a salary and have to try to survive the summer being unemployed, gift cards always make a welcome gift (I still have $ left on my Ale House card and I think about those parents and children that gave it to me, each time I go in there to eat). If you would really like to get an actual gift, its a good idea to get something practical. Some parents at Christmas got their teachers those large cups with the lid and straw and put the teachers names on them. Those cups get used A LOT. If you get to know your teacher's personal taste, that definitely helps (if she is a Gator fan, loves coffee, or going to movies). The one thing I would stay away from is "World's Greatest Teacher" gifts (unless your child insists, of course, which my child did one year).
Another thing that always drives me crazy is how they always have "Teacher Appreciation Week" 2-3 weeks before the end of the school year. I used to always stress myself out wondering if I should get a gift for both occasions. My thought on this is, that you should have your child draw a picture or make a card, or craft or bring in a picked flower for Teacher Appreciation Week. Keep it small and make it more about your child. The end of the school year is the better time for parents to say thank you. Just remember that when it comes down to it, just acknowledge and thank your teacher for helping your child this year. Whether you are able to do more or not, that is the most important thing.