Small, dark brown (matte) vase with initials "M D" and "C-11" ? (photos)

by Lawrence
(Rutland, Vermont)

I have acquired a short, dark brown clay vase (approx 6 inches in height and 4 inches at its widest) with inscribed initials "M D" and "C - 11". Please refer to photos.

The brown glaze is heavy and covers the entire vase, except for an uneven border at the very bottom (approx 1/2 inch). The vase is hand-thrown, and very sturdy looking.
Any information regarding this piece would be very much appreciated.
Thank you!