$re = '/(?:\r|\n) *([^\n=\.]+)(?<=\S) *= *(.+)/m';
$str = 'This is multiline text that needs to be correctly parsed into key-value pairs, excluding all other information.
Section One:
First key = Value One
Second key = Value Two
Section Two:
Third key = Value Three
Fourth key = Value Four
Fifth key = Value Five
Section Three:
Sixth key = Value Six
Seventh key = Value Seven
Eighth key = Value Eight';
preg_match_all($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