Constant data can be embedded in XAML.
<Window.Resources>
<t1:collectionType x:key="listName">
<t2:itemType prop="value" .../>
<t2:itemType prop="value" .../>
....
</t1:collectionType>
<t3:instancetype x:key="itemName" prop="value..."/>
</Window.Resources>
The data is bound to a property of a control using:
prop="{StaticResource key}"
Where key is the x:key of the item in the resource. In code the resource can be accessed using the FindResource method, again using the x:key.