public function addingItem($id)
    {
      $product = Product::where('id', $id)->firstOrFail();

      Cart::add(array(
        'id' => $product->id,
        'name' => $product->title,
        'price' => $product->price,
        'quantity' => 1,
        'attributes' => array(),
      ));
      Session::flash('success', 'This product added to your cart successfully.');
      return redirect()->back();
    }

public function addingItem($id)
    {
      $product = Product::where('id', $id)->firstOrFail();
//newly added
      foreach($product->suboptions as $subs) {
        $title = $subs->title;
        $price = $subs->price;
      }

      $customAttributes = [
            'attr' => [
                'label' => $subs->title,
                'price' => $subs->price,
            ]
        ];

      Cart::add(array(
        'id' => $product->id,
        'name' => $product->title,
        'price' => $product->price,
        'quantity' => 1,
        'attributes' => array($customAttributes), //and added here
      ));
      Session::flash('success', 'This product added to your cart successfully.');
      return redirect()->back();
    }

Cart::add(array(
  array(
      'id' => 456,
      'name' => 'Sample Item 1',
      'price' => 67.99,
      'quantity' => 4,
      'attributes' => array()
  ),
  array(
      'id' => 568,
      'name' => 'Sample Item 2',
      'price' => 69.25,
      'quantity' => 4,
      'attributes' => array(
        'size' => 'L',
        'color' => 'blue'
      )
  ),
));