Ham and Potato Corn Chowder

Name: Ham and Potato Corn Chowder
Ingredients: 2 tablespoons butter (for sautéing); 2 stalks celery (finely chopped); 2 carrots (peeled and diced); 1 medium onion (chopped); 5 medium red potatoes (peeled and cubed); 2 cans (14.5 oz each chicken broth); ¾ teaspoon dried oregano; ½ teaspoon dried thyme; 1 bay leaf; Salt and freshly ground black pepper (to taste); 2 cups cooked ham (diced); 2 cups corn (fresh or frozen); 4 tablespoons butter (for roux); ⅓ cup all-purpose flour; 3 cups whole milk; ½ cup sour cream or heavy whipping cream; 6 slices bacon (cooked and crumbled); Chopped green onions (for garnish)