Funny you should mention this topic - I am right in the middle of the week where we teachers are receiving lots of gifts, and unfortunately, most of mine are unusable because they are all scented things, and I am allergic! Parents love to give teachers lovely gift-wrapped soaps, bath oil, perfumes, hand lotion, etc. but I cannot use the stuff. I have recently begun donating all this stuff to a homeless shelter for street kids. They often need toiletries for showers, and for when they get established in their own apartments.
On the other hand, I have received some very nice gifts too. Chocolate tops my list, as do homemade baking and homemade ornaments, and gift certificates are always welcome! I bought myself some nice treats last year with those!
As for me, I always tried to give my kids' teachers somethig personal, homemade, or thoughtful. I wanted them to know they were truly appreciated.
Funny story. Yesterday I recieved a beautiful calendar from a little boy. Hid mother told me that she picked it, because when she asked him, he told her to buy me a shovel!