How to store variable from option value to controller and save it in database with Laravel?

I'm trying to save variables from my view to controller and then save it in databases but im getting MethodNotAllowedHttpException.

Here are my view

<form method="POST" action="">

      <div class="form-group">
        <label name="nim"><h3>NIM :</h3></label> &nbsp;
        <select name ="mahasiswasn" class="selectpicker" data-live-search="true" data-width="500px" title="Choose the Student Number">
        @foreach($nim as $nm)
          <option value=""></option>
        @endforeach
      </select>
      </div>

      <div class="form-group">
        <label name="matkul"><h3>&nbsp;MK :</h3></label> &nbsp;
        <select name ="matkulsn" class="selectpicker" data-live-search="true" data-width="500px" title="Choose the subject">
        @foreach($matkul as $mkl)
          <option value=""></option>
        @endforeach
      </select>
      </div>

      <div class="form-group">
        <label name="hari">Hari :</label>
        <input id="hari" name="hari" class="form-control">
      </div>

      <div class="form-group">
        <label name="status">Status :</label>
        <input id="status" name="status" class="form-control">
      </div>

      <input type="submit" value="Add Absensi " class="btn btn-success btn-lg btn-block">
      <input type="hidden" name="_token" value="">

    </form>

My Controller (AbsensiController)

public function store(Request $request)
    {
           $this->validate($request,array(
                'nim' =>'required',
                'matkul' =>'required',
                'hari' =>'required',
                'status' =>'required'
                ));

            //store in database
            $post = new PostAbsensi;

            $post->nim = $request->get('mahasiswasn');
            $post->mk = $request->get('matkulsn');
            $post->hari = $request->get('hari');
            $post->status = $request->get('status');

            $post->save();

            Session::flash('success','data successfully saved!');

            return redirect()->route('absensi.show', $post->id);
    }

My Routes :

Route::resource('absensi','AbsensiController');

Please Help, thank you for your attention.

via Chebli Mohamed