Amy's three best things - Philippa Pearce

Amy is going on her own to stay with her grandmother for three nights and takes her three best things. As each night passes, she feels dreadfully homesick but then she remembers her three best things.
One by one they magically come to life and transport her back home where she can see everything is well. But on the third night her house is deserted and Amy is distraught and unconsolable. However, she soon learns it is because her mother was missing her so much that she has come to visit - and there she is to reassure and comfort Amy.