why I am getting TokenMismatchException in VerifyCsrfToken.php line 53 in laravel 5.1 while i am using csrf token

I am suffering this problem that says TokenMismatchException in VerifyCsrfToken.php line 53: I am using {!!Form::open()!!} {!!Form::close!!}. When I click add Button in my form with empty field for first time it shows me error as I set validation rule. But when I click Add button again without refreshing the page it shows me TokenMismatchException error. I have checked with dd() and it shows me the token like this:

 `array:3 [▼
 "_token" => "5dXwRHbz4GNY1tx9OVeWPcOkirVIm0YtpkZufFbr"
 "menu_name" => ""
 "menu_price" => ""`

here is my form code

{!! Form::open(array('route' =>'upcoming.store', 'method'=>'POST')) !!}
                    <div class="col-lg-6 col-sm-offset-3 top-spacing">
                        <input type="text" name="menu_name" placeholder="Menu Name.." class="form-control">
                    </div>
                    <div class="col-lg-6 col-sm-offset-3 top-spacing">
                        <input type="text" name="menu_price" placeholder="Menu Price.." class="form-control">
                    </div>

                    <div class="col-sm-2 col-sm-offset-8 top-spacing">
                        <button class="btn btn-success">
                            Add +
                        </button>
                    </div>

                </div>
                {!! Form::close() !!}`

Here is my controller store function

 public function store(Request $request)
{
    dd($request->all());
    $this->validate($request, array(
        'menu_name'=>'required',
        'menu_price'=>'required',
        ));
    $upcoming = new Upcomingfood;
    $upcoming->menu_name=$request->menu_name;
    $upcoming->menu_price=$request->menu_price;
    $upcoming->save();
    Session::flash('success','Food Menu Added Successfullly');
    return redirect()->back();

}

thanks in advance. It will be really helpful for me if I get my answer as I am new in Laravel.

via Chebli Mohamed