Bay leaves add depth of flavour to soups and sauces. The California variety has a bright green colour and a beautiful long leaf (making them great for craft work), with a strong, slightly astringent flavour. The Turkish bay leaves have a softer, more subtle flavour and are more commonly used in most cooking.
Dried bay leaves can last for a long time, but do eventually lose their flavour. Test yours by bending them slightly – they should have a bit of flexibility, and when you do break them, they should still have an aroma.