2 kittens came to my garden and they are 4 weeks old what else can they eat insteadof tuna or cat food or milk?

they came when the door was open and tried to come inside with me so i blocked them because i thought they would go back but i saw through the window like 10 miniutes later and they were still there so gave them tuna and milk they ate it very quicky and then they both lied down and slep in my garden by the way they dont have rabies of anything beacuse they looked normal and healthy. but what esle could cats eat other than milk and tuna and cat food