<ItemsControl ItemsSource="{Binding boardSquares}">
            <ItemsControl.ItemsPanel>
                <ItemsPanelTemplate>
                    <UniformGrid x:Name="canvasGrid" Background="Black" Columns="5" Rows="5" Margin="5">

                    </UniformGrid>
                </ItemsPanelTemplate>
            </ItemsControl.ItemsPanel>
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <Rectangle Fill="Gray" Stroke="BlanchedAlmond" DragEnter="ListBoxDestination_DragEnter" Drop="ListBoxDestination_Drop" />
                </DataTemplate>
            </ItemsControl.ItemTemplate>
</ItemsControl>

private void ListBoxColor_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        startPoint = e.GetPosition(null);
    }

    private void ListBoxColor_MouseMove(object sender, MouseEventArgs e)
    {
        Point mousePos = e.GetPosition(null);
        Vector diff = startPoint - mousePos;
        if (e.LeftButton == MouseButtonState.Pressed &&
            (Math.Abs(diff.X) > SystemParameters.MinimumHorizontalDragDistance ||
            Math.Abs(diff.Y) > SystemParameters.MinimumVerticalDragDistance))
        {
            // get the dragged listbox item
            ListBox listBox = (ListBox)sender;
            ListBoxItem listBoxItem = findAncestor<ListBoxItem>((DependencyObject)e.OriginalSource);
            if (listBoxItem != null)
            {
                // Find the data behind the listBoxItem
                string theItem = listBox.ItemContainerGenerator.ItemFromContainer(listBoxItem).ToString();
                // initialize drag and drop
                // create a DataObject containing the string to be "dragged"
                DataObject dragData = new DataObject(typeof(Rectangle), theItem);
                // initialize the dragging
                DragDrop.DoDragDrop(listBoxItem, dragData, DragDropEffects.Move);
            }
        }
    }

    private static T findAncestor<T>(DependencyObject current)
        where T : DependencyObject
    {
        do
        {
            if (current is T)
            {
                return (T)current;
            }
            current = VisualTreeHelper.GetParent(current);
        }
        while (current != null);
        return null;
    }


    private void ListBoxDestination_DragEnter(object sender, DragEventArgs e)
    {
        if (!e.Data.GetDataPresent(typeof(Rectangle)) || sender == e.Source)
        {
            e.Effects = DragDropEffects.None;
        }
    }

    private void ListBoxDestination_Drop(object sender, DragEventArgs e)
    {
        if (e.Data.GetDataPresent(typeof(string)))
        {
            Rectangle theItem = (Rectangle)e.Data.GetData(typeof(Rectangle));
            Rectangle cellItem = (Rectangle)sender;
            cellItem.Fill = cellItem.Fill;
        }
    }
}