I've done a few "thanks" poems for children, though not explicitly for the holiday of Thanksgiving. Here's one that was in
Spider. Forgive both the size and the way the page didn't lie flat when I took a picture of it.
The form is a "mesostic." It's like an acrostic, but the letters can line up anywhere in the line instead of the first letter of the line. I've done tons of these and I've always thought the letters should be left blank so kids can fill them in and use them as clues to solving the riddle, but the folks at
Spider preferred it this way (I think they don't like anything that encourages kids to mark up the magazine since so many of them are distributed in libraries).
