- I assume that she is Samuel's daughter.
B.S. 5, Folio 381, Nov. 23, 1832: Mary Lansdale gets Deed from Honore Martin, Trustee: Shows a decree of July 21, 1828 to sell the land of Honore Martin. Sale to Samuel Pumphrey, "resurvey on Valentine's Garden Enlarged, being Lot No. 1, 9/16 of an acre that Samuel Pumphrey sold to his daughter the said Mary Lansdale."
B.S. 2, fol. 34: Polly Lansdale gets Deed of Givt from Samuel Pumphrey, Oct. 28, 1828, who mentions her as his daughter Polly Lansdale, the wife of John Lansdale: lot lying on the turnpike leading from Rockville to Georgetown, &c.
She is on the Maryland Mysteries page.