Soda crackers are the usual Yankee accompaniment to chowders, eaten with and crumbled in the soup. If you would like to make your own, here is an old recipe.
Mix enough sour milk, in which the soda has been dissolved, into the flour to make a very stiff dough. Knead well, working in the butter and lard, and roll out very thin. Cut, shaping the crackers as you wish, sprinkle with coarse salt, and prick them in patterns with a fork. Bake the soda crackers in a moderate oven (350 degrees F) until they are crisp.