Heat oil in a large stock pot over medium high heat; add onions and celery and sauté until translucent, about 5-7 minutes. Add garlic and sauté for one more minute. Carefully pour in stock and scrape the bottom of the pan to release any brown bits. Stir in the black beans, black eyed peas, and tomatoes. Add the butternut squash and corn. Add herbs, stir and bring to a boil. Once boiling, reduce to a simmer, cover with a lid and cook for 1 1/2 hours, stirring every 1/2 hour to prevent sticking. Add more stock or water if beans and squash absorb too much liquid.