Lower, Mark A (1860) Patronymica Britannica: a dictionary of the family names of the United Kingdom. London: J.R. Smith. Public Domain.
YELVERTON
As described in historical dictionaries
Patronymica Britannica (1860)
YELVERTON. A parisli in Norfolk, where the family appear to have dwelt in early times. The extinct Earls of Sussex sprang from Andrew de Yelverton of that county, who flourished temp. Edward II.