According to the nearby sign:

The Moore Family

Descendants of Clement C. Moore, Author of a “A Visit from St. Nicholas“.

The Moore family resided in Ossining from about 1839 until the early years of this century. They were descendants of Clement Clark Moore, the well-kown scholar and writer who lived from 1779 to 1863.

The family resided in one of Ossining’s oldest houses, located near the river in the Brayton Park area. The house, known as “Moorehaven”, ws built around 1740 by a Dutch family named Auser, original settlers in the area. It was the scene of a Revolutionary War skirmish between an American raiding party returning from behind British lines, and a British detachment that had pursued them from the Bronx.

Clement Moore, although a visitor to Ossining, was not known to have resided here other than for brief visits. His principal home was in the Chelsea section of Manhattan where he wrote his immortal “A Visit from St. Nicholas” for his children’s Christmas celebration in 1882. The now famous poem was published the next year. Mr. Moore lter resided for many years in Newport, Rhode Island. He is not buried in Dale Cemetery.

The Moore family were prominent Ossining residents. They were members of Trinity Church and donated the clock and chimes to the church in 1894.

For some reason this plot made me think of the inscription on another Moore grave – This one in Boothill Graveyard, Tombstone, Arizona.

HERE
LIES
Lester Moore,
FOUR SLUGS
FROM A 44
NO LES
NO MORE