Accessing UploadedFile from request/input is null

I am trying to send some files via mail:

  Mail::send('vendor.notifications.email', $maildata, function($message) use ($input)
  {
    $message->to(Config::get('constants.bywood_mail'));
    $message->subject(Lang::get('platform.message_new_user_subj'));
    $message->from(Config::get('constants.bywood_mail'));

    if(Input::file('files')){
      foreach(Input::file('files') as $file) {
        $message->attach( $file->getRealPath(), array(
          'as' =>  $file->getClientOriginalName(), 
          'mime' =>  $file->getMimeType())
        );
      }
    }

But although

  var_dump($input);

shows that there are file pathes available:

  'files' => 
    array (size=3)
      0 => string 'layer-slider-rtl.js' (length=19)
      1 => string 'master-slider-fw.js' (length=19)
      2 => string 'mouse-wheel.js' (length=14)

the following just gives me null values:

  var_dump(Input::file('files'));
  var_dump($request->file('files'));

I am trying to solve this problem for days already and appreciate any help. Please note that I am trying to do this in the RegisterController class where I am overriding the register method.