$_POST is empty after 'save_post' action

I’m new to plug-in development, but not wordpress, itself. I think I’m doing something wrong but cannot figure out what.

I created a new metabox on the ‘edit post’ page. I put a checkbox in it.
Based on the checkbox being ticked or not, it will create/update a custom field with a value.
My problem is after I hit ‘update post’, the page reloads, but $_POST is empty.

/* Add a new meta box to the admin menu. */
	add_action( 'admin_menu', 'fm_create_meta_box' );

/* Saves the meta box data. */
	add_action( 'save_post', 'fm_save_meta_data' );

/* Function for adding meta boxes to the admin. */
function fm_create_meta_box() {
	add_meta_box( 'post-meta-boxes', __('Featured Post'), 'display_post_meta_boxes', 'post', 'side', 'high' );
}

function display_post_meta_boxes() {
	global $post;

	var_dump($_POST);

	if(isset($_POST['chkFeatureMe'])){
		$check = $_POST['chkFeatureMe'];
	} else {
		$check = 'false';
	}

	if(get_post_meta($post->ID, 'isFeatured', true)) {
		?>
		<input type="checkbox" id="chkFeatureMe" name="chkFeatureMe" value="true" checked="checked"> Feature this post?<br/>
		<?
	} else {
		?>
		<input type="checkbox" id="chkFeatureMe" name="chkFeatureMe" value="true"> Feature this post?<br/>
		<?
	}
}

function fm_save_meta_data() {
	global $post;
	$isToBeFeatured = $_POST['chkFeatureMe'];
	$retval = add_post_meta($post->ID, 'isFeatured', $isToBeFeatured, true);
	if (!$retval) {
	  $retval = update_post_meta($post->ID, 'isFeatured', $isToBeFeatured, true);
	}

}

You can see I do a var_dump on the $_POST array and it outputs “array(0) { }”

This code should be able to be cut and pasted into a new plug-in as is.