Compare the 1860 and 1870 censuses: it seems that some of the children are likely to be biological children just of Pleasant's second wife, Elizabeth.
https://www.findagrave.com/memorial/91298726/henry-grayson
https://www.findagrave.com/memorial/145849076/lucy-grayson
The gravestone picture included here was taken by Richard Grayson on a visit to the cemetery.