Green Pea and Ham Salad

1 (10 ounce) package frozen peas, thawed and drained

2 cups cubed fully cooked ham

1 cup shredded Cheddar cheese

¾ cup mayonnaise

2 tablespoons onion, chopped

1 ½ teaspoons mustard

Mix peas, ham, Cheddar cheese, mayonnaise, onion, and Dijon mustard in a large bowl. Cover and refrigerate at least 2 hours before serving.