Walnut Grove is a historic plantation home located in Clarksville, Maryland, Howard County, Maryland.The Walnut Grove plantation was built on land patented by Thomas Browne as Browne's Chance and Dorsey's Friendship. Revolutionary war patriot Col Gassaway Watkins built the stone manor house in 1780 with an onsite cemetery. The house was later purchased by his grandson Edwin Warfield. The propert was also owned by racetrack owner Frank DeFrancis and his daughter, Karin DeFrancis Van Dyke since 1989.In 1979 the property was entered into a historic preservation easement, with the intent to develop after a 25 year review. In 2001, the owners of Walnut Grove proposed developing 202 acres of the site near Sheppard Lane to develop 101 housing units with Goodier Builders.