The three Winnie and Walter books are collections of stories told by (and sometimes concerning) common characters. The books were published anonymously.
Uncle George's series does not have connected narratives. It was issued by the Congregational Sabbath School and Publishing Society in 1868. Because the series title loosely equated Tarbox with the name "Uncle George," several books issued in Leavitt & Allen's Uncle George's Juveniles in the 1850s appear to be erroneously attributed to Tarbox. These include The Child's Book of True Stories (1853) and The Mockingbird and Other Stories (1853). None are listed in bibliographies of his works published during or shortly after his lifetime -- and, indeed, precede by more than five years his first published juveniles. The misattributions may be the result of an initial miscataloguing carried over into The National Union Catalog.