What are Mary Call's plans for the cave?

Mary Call says that they will use heavy paper and linoleum to line the cave. In spring, they will make good money from herbing and gathering and will build their own house. She tells Romey that even though they will be troglodytes, they will still have to go to school, since living in a cave is no excuse for ignorance. She goes out to Old Joshua to find a cave. She finds a dark, cold cave that she thinks will work.