There are some great resources and preschool ideas at the Eric Carle website. I put my own spin on one and came up with a really fun Thanksgiving activity for the preschoolers.
We had been reading Eric Carle books all month, looking at the pictures, and talking about what is the same and what is different between them. I read a short biography about Eric Carle and a little bit about how he makes his illustrations. I told them how Mr. Carle uses lots of layers of color to make his pictures. Then, I had the kids rotate through stations doing different abstract Carle-inspired art. The splatter painted on top of designs they drew with poster crayons (my favorite new crayons), stamped then painted on top, drew with markers, painted with paint markers and water painted on coffee filters. The next day, we practiced cutting out circles from the papers we had painted the day before. The next week we talked about being Thankful and what things we were thankful for.