Remember: First and last point HAVE TO BE same. if not then expect 

error Invalid parameter value: 3037 Invalid GIS data provided to function st_geomfromtext

example

$mysqlStringPolygon = "POLYGON((1 1,1 5,4 9,6 9,9 3,7 2,1 1))";
        
$coords = new MapCoord();
$coords->polygon =  \DB::raw("ST_GeomFromText('$mysqlStringPolygon')");
$coords->save();

or use https://github.com/grimzy/laravel-mysql-spatial