"My Sheppard family line begins in Ireland with a John Sheppard, an Irish Quaker living from about 1662 to late 1600's. His son, William Sheppard, born in 1682 in Ireland and immigrated to East Nottingham, Chester County, Pennsylvania in…"
Cahir in Tipperary was a well known Quaker area. There was also a Quaker burial ground in Ballykelly, North Tipperary, where some Sheppards are buried. Perhaps that is the origin of your Sheppards.