Thanksgiving Veggie is a term used to describe two popular vegetables that are traditionally served during the Thanksgiving holiday in the United States. The first vegetable is the YAM, which is a starchy root vegetable with a sweet flavor. It is usually cooked and mashed before being served. The second vegetable is the sweet potato, which is a tuberous root vegetable with a slightly sweet flavor. It is often roasted or baked before being served. Both of these vegetables are popular side dishes for Thanksgiving dinner.