I used to love this book about a family that went camping, the two kids went off to explore, and get lost in the brush. They find an abandoned home on a lake, that they end up staying at, and eat fish they catch from the lake, and berries from the overgrown garden. Eventually a few days later their big black shaggy dog (I think named Sadie) finds them and returns them back to their family. The cover was beige with an oval frame, the shaggy dog's face coming through the oval. Thanks for any help!