Here are a couple Thanksgiving writing ideas:
Writing Fix has a lesson I love called "Turkey Protests." It is based on the mentor text My Lucky Day by Keiko Kasza where a pig convinces a wolf not to eat him.
The idea of the lesson is to write from the point of view of a turkey convincing humans not to eat you. The lesson includes ideas, student samples, and graphic organizers for you to print out. While doing this lesson, I like to also look at other persuasive texts or discuss things like examples of persuasion in media or billboards. Think of Chick Fil A and the cows convincing you to eat chicken. You could draw posters of turkeys saying "Eat Beef" or "Eat ham."
We are going to use the interactive Persuasive Map at Read Write Think to help us.
I also am planning on doing the disguise a turkey assignment. Even though it is meant for younger grades, my fifth graders have always enjoyed it in the past. Here is a link to a free one on Teachers Pay Teachers. My students will write a paragraph describing their disguised turkey. You also could write a biography of the disguised turkey or a creative story about the disguised turkey. You could incorporate the disguised turkey into the Persuasive "Don't eat me" assignment.