The triangle is a single-ear variant of a Brewerton Eared-Triangle. It's Late Archaic. I have found quite a few in Ma and RI. It matches exactly 2 of the examples shown in Jeff Boudreau's "A New England Typology of Native American Projectile Points", the most recent and best typology guide for the New England region. Brewerton Eared Triangles that display a narrow isoceles form are not as common as wider variants but the single very slight ear is a dead give away as to the type: the single eared variant of a Brewerton Eared Triangle. While such triangles usually have 2 slight ears, the single eared form is not at all uncommon. Don't know why they made them with just one ear, though. Both nice finds!