Miss Sadie McGee Who Lived in a Tree — Mark Kimball Moulton

A young boy flying a kite discovers a staircase in a tree trunk that leads to a treehouse where Sadie lives. After drinking tea, "which she served graciously to three squirrels and to me," the boy rescues his kite and leaves. But now he know why Sadie lives "contentedly in the hickory tree by the sea."