I wanted to display the featured image (post thumbnail) of one post from the most latest blog posts.

I didn't want a plugin as the image was being displayed in some custom header background code... that at the top of the home page of this site.

I couldn't find any code online that I could copy and paste and with a few similar recent and random post code snippets, I created my own PHP code snippet to display the featured image of one post from the latest X posts.

The code below uses the WordPress wp_get_recent_posts() function using appropriate arguments in the $arg variable to retrieve the most recent 30 posts.

Then, one random post is found that contains an featured image, as not all my posts contain a featured image.

Once the random post containing a featured image is found, the featured image URL is displayed.

You may wish to display other aspects of the post including the title and content, and these are contained the $onepost array which contains the following variables and their values for the one random post.

[ID]
[post_author]
[post_date]
[post_date_gmt]
[post_content]
[post_title]
[post_excerpt]
[post_status]
[comment_status]
[ping_status]
[post_password]
[post_name]
[to_ping]
[pinged]
[post_modified]
[post_modified_gmt]
[post_content_filtered]
[post_parent]
[guid]
[menu_order]
[post_type]
[post_mime_type]
[comment_count]
[filter]

Note that the featured image URL is not a variable in the $onepost array, and I used the WordPress function get_post_thumbnail_id() with the one random post ID to retrieve the one featured image URL.

The PHP code to get 1 random WordPress post from recent X posts.

$numberofposts = 30;
$args = array(
    'numberposts' => $numberofposts,
    'orderby' => 'post_date',
    'order' => 'DESC',
    'post_type' => 'post',
    'post_status' => 'publish',
    'suppress_filters' => true );
$recent_posts = wp_get_recent_posts( $args );
$randompost = rand(0,($numberofposts-1));
$onepost = $recent_posts[$randompost];
while ( !has_post_thumbnail($onepost['ID']) )
{
	$randompost = rand(0,($numberofposts-1));
	$onepost = $recent_posts[$randompost];
}
echo wp_get_attachment_url( get_post_thumbnail_id($onepost['ID']) );