Inscription:

SACRED
In the memory of
SARAH V. McCULLOUGH
WHO DIED
July 10, 1849
Aged
8 years.

Sarah V. McCullough
Birth: Unknown
Death: 10 July 1849
Burial: Cold Water Cemetery, Florissant, St. Louis County, Missouri

Notes:
Note the similarity of tombstone inscriptions and the dates of the deaths of George McCullough and Sarah V. McCullough. There is no indication Sarah is the daughter of George, but it seems likely.