Really Truly Bingo by Laura McGee Kvasnosky
A little girl wants her mother to play with her but - surprise surprise - her mother is too busy. She asks what she can do and her mother tells her to use her imagination. And she does! She imagines up a dog named Bingo who encourages her to do things she shouldn't and she does manage to make a pretty big mess in the yard, which gets her in some trouble with her mom. But nothing she can't handle with the help of her imaginary pal, Bingo.
The illustrations are really great! Again with the thick black outlines that I love so well, these are simple but full of detail at the same time. You could easily talk about each page for a long while with a child you are reading to. They are also readable enough from a distance to use as a storytime book.