While we didn't do an end of the year gift this year, we have in the past. In our community, it's pretty common to give gifts at the end of the year as well as giving one around the holiday season.
This year though, I decided their teachers have had enough of the gifts they might not use and already have etc. And without really knowing what kind of food they like to eat, etc. I decided to do something different this year.
My kids are writing a letter this summer to their teacher thanking them for being a great teacher and sharing their favorite things about the school year.
Edited to add - not saying at all that a material gift isn't a good idea! I just really didn't have a feel this year of what their teacher's personal interests are! If there's something specific, like the book etc. that they would love, then by all means!

This year was just different for us, that's all.