/**
 * Display field value on the admin order edit page..
 *
 * PHP Custom Feild Value
 * 
 * 
 */

add_action( 'woocommerce_admin_order_data_after_billing_address', 'my_custom_checkout_field_display_admin_order_meta', 10, 1 );
function my_custom_checkout_field_display_admin_order_meta($order){
    echo '
'.__('Store Location').': ' . get_post_meta( $order->id, 'My Field', true ) . '
';
}