Array to string conversion laravel 5.5 when seeding data

Array to string conversion

(SQL)

 `insert into `group_members` (`id`, `group_id`, `alias`) values (1, 20, Lilian Marvin PhD)`

$users =  User::where('role_id','=',3)->select('id','display_name')->get();

        foreach ($users as $user) {
            $groups =  Group::select('id')->get()->toArray();   
            // echo $user->display_name ." " .$user->id ."<br/>"; 

            DB::table('group_members')->insert([
                'id' => $user->id,
                'group_id' => array_random($groups),
                'alias' => $user->display_name
            ]);
        }

in the array_random, I believe there's an error

via Chebli Mohamed