SimplePie does not have built-in filtering functions (yet). However, you can selectively show only the items you wish:
$feed = fetch_feed($rss_url); // specify the source feed$limit = $feed->get_item_quantity(20); // specify number of items$items = $feed->get_items(0, $limit); // create an array of items$ignoreGUIDs = array("http://example.com/feed?id=1", "http://example.com/feed?id=2");foreach ($items as $item) : if(!in_array($item->get_id(false), $ignoreGUIDs)){ echo $item->get_description(); }endforeach;The get_id() method returns an array of the item's <guid>, <link>, and <title> tags, each of which the in_array() clause then searches for a match of each of your $ignoreGUIDs. If there are no matches, it means the item's GUID is not in your exlusion list and so the item is shown (by echo).