How is Mrs. Frisby's home described in the novel, Mrs. Frisby and the Rats of Nimh?

Mrs. Frisby and her children, a family of mice, live in a "slightly damaged cement block [that] . . . lay almost completely buried" in Mr. Fitzgibbon's field. The furnishings of this house are "bits of leaves, grass, cloth, cotton fluff, and other soft things Mrs. Frisby and her children had collected." The Frisbys stay here during the winter, when living in the woods becomes too harsh because of the scarcity of food.