Hamburger. Beef minced (US: ground) with onions and formed into a thin patty. It is commonly then grilled and served on a soft white bread roll with a gherkins (US: dill pickle) and a choice of sauces. The beef burger is a very good example of something which, when made at home with good quality beef and served with a thoughtful sauce, can be a delight but which, in mass production, is pretty horrible.
Pastry shells or shells generally. These could either be filled with savoury stuffings, such as creamed mushrooms or shellfish, or with custard or fruit.