Round corner button in WPF

<UserControl x:Class="WindowsFormsApplication8.UserControl1"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Height="154" Width="177">
    <Grid>
        
        <Rectangle Name="rectangle1" Stroke="Black" RadiusX="10" RadiusY="10" >
        </Rectangle>

        <Button Name="rectangle2" Foreground="Black" Margin="3,3,3,3" >
            <Button.Background >
                <LinearGradientBrush StartPoint="0,0" EndPoint="1,1">
                    <GradientStop Color="Green" Offset="0.0" />
                    <GradientStop Color="White" Offset="0.9" />
                </LinearGradientBrush>
            </Button.Background>
        </Button>
    </Grid>
</UserControl>