The Children's Literature Award is a specific award given by the American Library Association (ALA). While Lois Lowry has received many other awards for her writing, she has never won this specific one.
It's possible you are thinking of another award she won, such as:
* The Boston Globe-Horn Book Award for "Number the Stars"
* The Margaret A. Edwards Award for her body of work
* The National Book Award for her book "The Giver"
Let me know if you'd like to know more about Lois Lowry or any of her books!