query a newly created table using $wpdb

you doing something wrong your $result query returns multidimensional array of rows and each row has an array of keys values, try this, not tested but will work.

<?php
global $wpdb;
$result = $wpdb->get_results ( "SELECT * FROM  $wpdb->forms" );
foreach ( $result as $key => $row ) {
      echo $row->ID.'<br/>';
}
?>