Binding a WPF Button CommandParameter to the Button itself in DataTemplate

Answer like Miklós Balogh said, or you can:

<Button x:Name="MyButton" Command="{Binding Command}" CommandParameter={Binding ElementName=MyButton ... /> 

<Button Command="{Binding Command}" 
        CommandParameter="{Binding RelativeSource={RelativeSource Self}}" />

Your Command property should be the generic version of the RelayCommand: RelayCommand<object> for instance.