Custom field

Put this code

<?php echo get_post_meta($post->ID, 'tumbnail', true); ?>

example

<p>Today's Mood: <?php echo get_post_meta($post->ID, 'tumbnail', true); ?></p>

<?php $key_name = get_post_custom_values($key = 'tumbnail');

                            echo $key_name[0]; ?>

under this code

    <?php while ( have_posts() ) : the_post(); ?>