How to serialize/deserialize simple classes to XML and back

Sometimes I want to emulate stored data of my classes without setting up a round trip to the database. For example, let's say I have the following classes:

public class ShoppingCart
{
    public List<CartItem> Items {get; set;}
    public int UserID { get; set; }
}

public class CartItem
{
    public int SkuID { get; set; }
    public int Quantity  { get; set; }
    public double ExtendedCost  { get; set; }
}

Let's say I build a ShoppingCart object in memory and want to "save" it as an XML document. Is this possible via some kind of XDocument.CreateFromPOCO(shoppingCart) method? How about in the other direction: is there a built-in way to create a ShoppingCart object from an XML document like new ShoppingCart(xDoc)?