simple shortcode plugin to display posts from the current day. I put it in a folder onthisday inside my plugins folder. Then make a page and add [onthisday] NB thewre are a few problems with thiis, use https://github.com/cogdog/wp-posted-today instead.

OnThisDay.php

<?php 
/*
There are some problems with this, use https://github.com/cogdog/wp-posted-today instead.
*/
 /*
 * Plugin Name: OnThisDay
 * Description: shortcode for posts on the current day
 * Version: 0.1
 * Author: John Johnston
 * Mostly borrowed from https://wordpress.stackexchange.com/questions/53462/on-this-day-php-code/53761
 * Author URI: http://johnjohnston.info
 * License:		 GPL2
 * License URI: https://www.gnu.org/licenses/gpl-2.0.html
 */
 
 function onthisday_register_shortcode() {
		 add_shortcode( 'onthisday' , 'onthisday_shortcode_routine' );
 }
 
 add_action( 'init', 'onthisday_register_shortcode' );
 
 
 function onthisday_shortcode_routine( $args ) {	 
 	return on_this_day();
 }
 
 
function on_this_day()
{
		$on_this_day = array(
		// Build the array using post date, and omit the year
		'monthnum' => date( 'n' ),
		'day' => date( 'j' )
 );
 
 //not sure I need this? JJ
 //filter_where at foot of code, I think it is for use on a post and will avoid the current post.
		add_filter( 'posts_where', 'filter_where' );
		$query = new WP_Query( $on_this_day );
		remove_filter( 'posts_where', 'filter_where' );

		if ( $query->have_posts() ) {
				$postYear = get_the_date( 'Y' );

				while ( $query->have_posts() ) {
						$query->the_post();
						$year = get_the_time( 'Y' );
						$queryYear = get_the_date( 'Y' );
						$month = get_the_time( 'm' );
						$day = get_the_time( 'd' );
						if ( $queryYear == $postYear ) {
						// I've comments this line out as I only want previous years JJ Should probably 
			//just sort filter_where function below
						// I use permalinks to link to. If you'd rather link to the day archive list, use get_day_link( $year, $month, $day ) instead of get_permalink.
						// This line compares the query year to the post year. If it's the same year, then add "Also from" so that it doesn't look like a duplicate link.
					//	echo '<a class="on-this-day" href="'.get_permalink( $query->ID ).'" title="On this day in '.$year.' - '.get_the_title().'">Also from '.$year.' - '.get_the_title().'</a><br> ';
						} else {
								echo '<p>On this day in <a class="on-this-day" href="'.get_permalink( $query->ID ).'" title="On this day in '.$year.' - '.get_the_title().'">'.$year.' - '.get_the_title().'</a></p> ';
						}
				}
				// Reset post data so it displays the original post.
				wp_reset_postdata();
		} else {
				// No posts to show
			 // echo "No Historical Posts On This Day";
		 echo "I don't seem to have posted on this day...";
		}
}


// Create a new filtering function that will add our where clause to the query
function filter_where( $where = '' )
{
		// Posts for all years before the current post date.
		//$where .= " AND post_date < '" . get_the_date( 'Y-m-d' ) . "'";
		// Filter on post ID instead
		$where .= " AND ID <> '" . get_the_ID() . "'";
		return $where;
}
 
 ?>