Incised bone handles such as you describe are extremely common in
18th and 19th c. sidtes in Virginia. Noel Hume illustrates one from
the 18thc. in his Artifacts book, and we've found them in both urban
and rural sites. We have also found cross-incised, or "x" markings,
but the couple instances I know of are both probably 2nd quarter of
the 19th c.
Dan Mouer