Thanksgiving is a holiday celebrated in the United States and Canada, during which people give thanks for the blessings of the past year. A traditional Thanksgiving dinner includes many side dishes, such as yams, YAM, and acorn squash. Yams are a starchy root vegetable with a sweet flavor, while YAM is a type of sweet potato. Acorn squash is a winter squash with a nutty flavor. All three of these items are popular side dishes for Thanksgiving dinners.