The way Rhythm is currently written, it will only return items with images as the random featured item. This is easy to change, however. If you open up custom.php you will see this block of code toward the top:
function rhythm_display_random_featured_item($withImage=true)
{
$featuredItem = random_featured_item($withImage);
$html = '<h2>Featured <span class="type-featured">Item</span></h2>';
if ($featuredItem) {
set_current_item($featuredItem); // Needed for transparent access of item metadata.
if (item_has_thumbnail()) {
$html .= link_to_item(item_thumbnail(), array('class'=>'image'));
}
// Grab the 1st Dublin Core description field (first 150 characters)
$itemDescription = item('Dublin Core', 'Description', array('snippet'=>150));
$html .= '<p><span class="title">' . link_to_item() . '</span> ' . $itemDescription . '</p>';
} else {
$html .= '<p>No featured items are available.</p>';
}
return $html;
}
Simply remove $withImage=true and $withImage from the first two lines and you should be able to display any items as featured.
FYI, we will likely be dropping the image requirement in future versions of the theme.
Hope this helps.