"Hank the Cowdog: The Case of the Burrowing Robot" by John Erickson (Book 42)

An unearthly being has burrowed in Sally May's vegetable garden. Hank tries to dig the space monster robot out of its hole. But when Sally May catches Hank in the ruined garden she blames him. Ashamed, Hank hits the road. Beginning his exile he runs into his old friend, Madame Moonshine. Will she help Hank clear his good name?