There is no corresponding GLOB_ONLYFILE directive. However, so long as you have named extensions, then you can simply use a glob pattern of
. If you don't have extensions, you'll need to make use of !is_dir.
Alternatively, you can pull a glob() of all records, and a glob of GLOB_ONLYDIR. Then you can use array_diff to remove the ones from the only directories glob from the entire glob which will leave you with only the files.
That should be doable as such (I can't test this where I am I'm afraid):
$sPath = realpath($directory) . '/*';
$aDirectories = glob($sPath, GLOB_ONLYDIR);
$aAll = glob($sPath);
$aFiles = array_diff($aAll, $aDirectories);
$aFiles should just be the files.