There’s a box that moved with Sarah Loveless and her husband from San Diego to Charleston, S.C., from Charleston to Dallas and from Dallas to Richland, Wash. The box, never unpacked, went into a closet or the garage each time. Contents: 20 to 30 electronics cords.

“The box was just always a part of our life,” says Ms. Loveless, 38. “It wasn’t useful to us. We weren’t doing anything with it except for moving it.”

Four...