how insert data json into database laravel?

I use ajax to get data json and send it to my controller, now I want to insert this data into table pointages help me please wher is the error. here is ajax code: he give me this error

 $('.add-all').on('click', function() {
        var items = [];
        let valu = $('#datePicker').val();
      $("tr").each(function(i,r){
        if ( i > 0 && $(r).find("input").first().prop("checked"))
        {  
          items.push({"matricule": r.cells[3].innerText, "salaire": r.cells[5].innerText, "date" : valu })
              }
                                      });
//ajax
$.ajax({ 
        method      : 'POST', 
        url       : 'mois', 
        headers: {
            'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
        },
        data      : {"items":items}, // pass in json format 
        success   : function(data) {
            console.log(data);
        },
        error : function(err){
            console.log(err)
        }
    });

//fin ajax 
      });  

Controller:

public function addMultiple(Request $request){
   foreach($request->get('items') as $item){
    $pointage = Pointage::create([
    'matricule' => $item->$item['matricule'], 
    'datep' => $item->$item['datep'],
    'solde' => $item->$item['salaire'] 
     ]);
}
return redirect("mois");
}

modele Pointage :

class Pointage extends Model
{
    /**
     * 
     *
     * @var array
     */
    protected $fillable = [
        'matricule', 'datep', 'solde',
    ];
}

table pointages:the other fields is nullable

  public function up()
    {
        Schema::create('pointages', function (Blueprint $table) {
            $table->increments('id');
            $table->integer('matricule');
            $table->date('datep');
            $table->double('nbrj');
            $table->double('prime');
            $table->double('solde');
            $table->timestamps();
        });
    }