Add items to a WordPress menu.

add_menu_item.php

// Filter wp_nav_menu() to add additional links and other output
add_filter( 'wp_nav_menu_menu-name_items', 'new_nav_menu_items' );
function new_nav_menu_items($items) {
    $homelink = '<li class="menu-item home"><a href="' . home_url( '/' ) . '">' . __('Home') . '</a></li>';
    $items = $homelink . $items;
    return $items;
}