求救，３歲孩子的午飯!

She goes to a preschool that we need to send her with lunch in a thermos because they cannot use microwave in school. Usually she likes dumpling, Baozi, noodle/pasta, wonton, but recently she's not eating any of it, then she gets really hungry and grumpy when I pick her up in the afternoon. What other things I can feed her? She doesn't like Mac&cheese, or sandwich at all. Please help! Thanks a lot!