$re = '/<\/p><br\s?\/?>/m';
$str = '<p>my text 1</p><br /> some other content<br /> <p>some other paragraph followed by an html line break</p><br><br /> etc...';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php