The best way to retrieve your public folder path from your Laravel config is the function:
$myPublicFolder = public_path();
$savePath = $mypublicPath."enter_path_to_save";
$path = $savePath."filename.ext";
return File::put($path , $data);
There is no need to have all the variables, but this is just for a demonstrative purpose.
Hope this helps, GRnGC