namespace TestWpfApplication
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MyPersonList mpl;

        public MainWindow()
        {
            InitializeComponent();
            mpl = new MyPersonList();
        }            
    }    

    public class Person
    {
        public Person(string firstName, string lastName)
        {
            FirstName = firstName;
            LastName = lastName;
        }        

        string FirstName { get; set; }
        string LastName { get; set; }

        //public override string ToString()
        //{
        //    return LastName;
        //    // return base.ToString();
        //}
    }

    public class MyPersonList : List<Person>
    {
        public MyPersonList()
        {
            Add(new Person("Иван", "Иванов"));
            Add(new Person("Пётр", "Петров"));
            Add(new Person("Сидор", "Сидоров"));            
        }
    }      
}

<Window x:Class="TestWpfApplication.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:obj="clr-namespace:TestWpfApplication"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <obj:MyPersonList x:Key="PersonData" />                 
    </Window.Resources>
    <Grid>
        <ListBox Height="311" HorizontalAlignment="Left" Name="listBox1" VerticalAlignment="Top" Width="163" 
                 ItemsSource="{Binding Source={StaticResource PersonData},  Path=LastName, Mode=OneWay}" />
    </Grid>
</Window>