The Collaborative International Dictionary
Footstone \Foot"stone`\ (?; 110), n. The stone at the foot of a grave; -- opposed to headstone.
Wiktionary
n. A gravestone placed at the foot of a grave; typically smaller than a headstone, and frequently resembling a large cobblestone.
Wikipedia
A footstone is a marker at the foot of a grave. The footstone lies opposite the headstone, which is usually the primary grave marker. As indicated, these markers are usually stone, though modern footstones are often made of concrete, or some metal (usually bronze) in the form of a cast plate, which may or may not be set in concrete. The footstone may simply mark the foot of a grave, serving as a boundary marker for the grave plot, but more often provide additional information about the interred decedent. A footstone usually contains the initials of the person whose grave it marks.
Usage examples of "footstone".
Ruins stood here: a pale footstone half sunk into the loam, a section of standing wall protecting nothing but trees, a crumbling arch grown over with rapevines, a stretch of man-laid road running parallel to the path.
Alexandra kept threatening to dig up and replace with hibiscus to the square marble footstones leading to the front of the house.