In a medium heavy pot, heat oil over medium. Add celery, carrots, onion, and garlic; season with salt and pepper. Cook, stirring occasionally, until vegetables are soft, 9 minutes. Add oregano, tomatoes, broth, and Parmesan rind (if using). Increase heat to high and simmer rapidly until liquid thickens slightly, 5 minutes. Add pasta and cook, partially covered, until tender, 10 to 15 minutes. Add beans and cook until warmed through, about 3 minutes. To serve, remove rind and sprinkle with shaved Parmesan.