Sassy Lassie loves all things Vintage and this story is one she loved as a child and then read to her own children. I requested it through our library and J and I loved reading it last night. And then the phrase: "You're just what I need!" has become our farewell (at school in the am) and greeting (pick up at the day home). So tonight I found it on eBay, remarkably through a Canadian seller, and hopefully our own copy is in the mail soon.
It's a delightful story of a mother waking up in the morning and finding a "bundle" under the blankets and imagines all sorts of things that that bundle might be (of course, it's her child hiding). It was originally published as The Bundle in the early 1950s. The copy I found is a re-issue from the 1990s.