<esri:Legend.LegendItemTemplate >
<DataTemplate>
<StackPanel Orientation="Horizontal" Loaded="StackPanel_OnLoaded" >
<Image Source="{Binding ImageSource}" Tag="{Binding Tag}" ></Image>
<TextBlock Text="{Binding Label}" Background="Aqua"></TextBlock>
</StackPanel>
</DataTemplate>
</esri:Legend.LegendItemTemplate>
I am not sure which kind of layer you are referring to,
Currently I'm using a Graphics layer, where the objects are created an the symbol is set.
I set up the renderer, and it appear in the map