SLOW COOKER CLAM CHOWDER WITH SHRIMP

Name: SLOW COOKER CLAM CHOWDER WITH SHRIMP
Ingredients: 2 ribs celery (diced into bite-sized pieces); 3 large carrots (peeled and diced into bite-sized pieces); 1 medium red onion (diced into bite-sized pieces); 5-6 small Yukon gold potatoes (diced into bite-sized pieces); 1½ teaspoon salt; ¾ teaspoon black pepper; 1 teaspoon ground thyme; 1 quart (32 ounces) low-sodium chicken stock or broth; 1 can (15 ounces) can cream of mushroom soup (I used 98% fat-free); 4 cans (6.5 ounces per can) chopped clams (with the liquid); 2 tablespoons butter; 1 pound raw medium-sized shrimp (peeled, deveined, and chopped into bite-sized pieces); ¼ teaspoon Old Bay seafood seasoning; ¾ cups half-and-half; 3 tablespoons cornstarch; 1 tablespoon fresh lemon juice; oyster crackers for garnish (optional); fresh parsley for garnish (optional)