Sort and wash beans; place in a large bowl. Cover with water to 2 inches above beans; cover and let stand for 8 hours or overnight. Drain and rinse beans.
Combine beans and 8 cups water in a large Dutch oven; bring to a boil. Cover, reduce heat, and simmer 1 1/2 hours or until beans are tender.
Combine mushrooms and boiling water to cover in a small bowl. Cover and let stand 30 minutes or until tender. Drain and chop.
Place 2 cups cooked beans in a blender or food processor. Process until smooth; return pureed beans to pan. Stir in salt and pepper.
Heat 1 tablespoon oil in a large nonstick skillet over medium heat. Add onion, celery, and garlic; cook 10 minutes or until vegetables are tender. Stir in mushrooms, parsley, and the next 4 ingredients (through chiles); cook for 3 minutes, stirring frequently. Add onion mixture and chard to beans in pan; bring to a boil. Reduce heat, and simmer 10 minutes or until chard is tender. Ladle soup into individual bowls; drizzle with oil.
For someone looking for satisfying, low-(no) cholesterol, low-sodium recipes, this is a keeper! I use no-salt-added tomatoes and everything else as specified. The flavors are very satisfying! (Yes, the first time I made it from the printed version of recipe; saw there would be no liquid if I drained the cooked beans, so checked on-line for corrected version. I usually use boxed broth as the basis for soup, but water was fine with all the flavorings.)