In Chapter One, what does Marilyn find when she goes to Lydia's room?

When Marilyn opens the door to her daughter's room, she sees that the bed has not been slept in. Nothing seems out of place.... a pair of corduroys and a sock are on the floor, a row of science fair ribbons are on the wall, and Lydia's duffel bag is crumpled on the floor of the closet.