atcheck/database/seeds/SubjectsTableSeeder.php

<?php

use Illuminate\Database\Seeder;

class SubjectsTableSeeder extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        DB::table('subjects')->insert([
            'name' => 'Systemy Informatyczne UA0',
            'weekday' => 'Poniedziałek',
            'time' => '15:30',
            'user_id' => 2
        ]);

        DB::table('subjects')->insert([
            'name' => 'Systemy Informatyczne UA0',
            'weekday' => 'Wtorek',
            'time' => '17:15',
            'user_id' => 3
        ]);
    }
}