Use a meaty ham bone or ham hocks for this hearty senate bean soup. Senate bean soup is served in the senate restaurant every day. Idaho senator fred dubois purportedly requested the soup originally, which explains why his version includes mashed potatoes. These days, the soup is made with fewer ingredients. Included in the modern senate bean soup are some lightly sauteed onions and no potatoes, garlic, or celery. It's a very simple, stick-to-your-ribs soup. Prepared with celery, onions, parsley, garlic, potatoes and some spices, this bean soup delivers an extra delicious taste. Enjoy this warming soup on a chilly fall or winter day. The soup starts with a pound of dried beans. Navy beans are called for in the recipe, but great northern beans or a bean soup mixture are excellent substitutes. The potatoes are cooked and mashed, providing thickening and texture. Use leftover mashed potatoes if you have them. There are many other vegetables that can be added to the soup for flavor and color: diced carrots, red or green bell pepper, sliced mushrooms, turnips or rutabagas, and green beans or lima beans are just a few of the many possibilities. If you have leftover baked ham, dice it and add it to the soup along with the potatoes and vegetables. Serve the soup with hot baked cornbread or biscuits and a tossed green salad for a fabulous everyday meal. If you have leftovers, it's even better the next day. Or freeze the soup for a future lunch or dinner.