Here's something from the American Horticultural society:
River Farm's first English family was the Brents, a Catholic family who played an active role in the early colonial life of Maryland. Captain Giles Brent originally landed in Jamestown, Virginia but in 1638 returned from a trip to England accompanied by his sisters, Margaret and Mary, to settle in St. Mary’s County, Maryland. In 1647 the Brents settled near Aquia in Virginia. In 1653/54, Giles Brent obtained patents totaling 1,800 acres for his year-old son, Giles, Jr. Giles' wife was a princess of the Piscataway tribe of Native Americans who had been entrusted to Margaret Brent as a child by her father, a convert to Christianity. The grant of 1,800 acres in their child's name was named Piscataway Neck and included the land which is now River Farm.
Giles, Jr. was never at ease with the local Dogue tribe, or, it seems, anyone else. It has been stated that his encounters with the native tribe were a precursor to Bacon's Rebellion, and at home his treatment of his wife was so violent that she obtained a legal separation in 1679, the first in the Commonwealth of Virginia. Giles returned to England where he died in September of that year. Piscataway Neck passed to a cousin, George Brent, and through him to a brother-in-law, William Clifton, in 1739.
Upon inheriting title to the land, William Clifton renamed the property Clifton's Neck. By 1757, Clifton built a brick house on the property which, much enlarged and remodeled over the subsequent two centuries, now serves as the headquarters of the American Horticultural Society.
Clifton suffered business losses and as early as 1755 advertised part of his holdings for sale. Gentleman farmer George Washington of neighboring Mount Vernon was desirous of buying this land but because of what he described in his diaries as Clifton's "shuffling behavior" it was not until 1760 that Washington obtained clear title to the 1,800 acres for payment of £1,210 at the equivalent of a bankruptcy sale. To be fair to Clifton, not all the "shuffling" was his fault. At Mrs. Clifton's insistence only a portion of the property was first offered, the house and surrounding land to be retained for the Cliftons' use. Washington refused to buy the reduced package. It was not until Clifton was forced to submit to a commissioner's sale — Washington was a member of the commission — that Washington acquired the entire property and changed its name to River Farm.
Thus River Farm became the northernmost of Washington's five farms, and today's River Farm is located on the northernmost division of that property. Although Washington had patiently pursued the acquisition of the property, he never actually lived on or worked this land. Instead, he preferred to rent it, first in 1761 to tenant farmer Samuel Johnson who paid ever increasing amounts of his tobacco crop to Washington for the privilege. The farm was even once offered for sale in 1773, but instead Washington held on to it and later gave its lease as a wedding present to one Tobias Lear whose bride, Fanny Bassett, was Martha Washington's niece and widow of George Washington's nephew, George Augustine Washington.
Lear had come to Virginia in 1786 on the recommendation of a mutual friend to be secretary to Washington and tutor to Martha's two grandchildren. He was treated as a member of the family, taking his meals with them. He served Washington not only as secretary but as a personal confidante at Mount Vernon as well as in Philadelphia and New York while Washington served as the young nation’s first President. He was at Washington's side when he died. In his will, Washington gave Lear use of the farm, rent free, for his lifetime. Tobias' wife Fanny predeceased him, and he installed his mother-in-law and children at the farm while he preferred to reside in Georgetown. It is said he died there, a suicide, in 1816. However, evidence of his spiritual presence at River Farm continues to this day.
Tobias Lear had called the property Walnut Tree Farm. Today, in the meadow below the “ha-ha” wall, three venerable old black walnut trees still stand, reminders of the 18th century landscape that Lear and Washington knew. Another of River Farm’s trees with strong associations with Washington is the Kentucky coffee tree, so named for its native origin and its seeds use as a coffee substitute. Washington introduced the species to Virginia when he returned to Virginia from one of his surveying trips in the Ohio River valley and successfully germinated seeds he had collected there. There are several specimens of the Kentucky coffee tree at River Farm, descendants of those first trees grown by Washington.
The oldest tree standing on River Farm today is the immense Osage orange. This specimen, the largest in the country, is located in the shade garden to the north of the main house. It is believed to have been a gift from Thomas Jefferson to the Washington family. It is known that Jefferson received seedlings of the Osage orange from the Lewis and Clark expedition of 1804-06.
After Tobias Lear's death, the farm was occupied by two generations of the Washington family: George Fayette Washington, a nephew, and Charles Augustine Washington, a great-nephew. In 1859, a century after Washington purchased the property from Clifton, Charles Augustus sold 652 acres of River Farm to three Quaker brothers, Stacey, Isaac, and William Snowden of New Jersey. The Snowdens and other Quaker families came to the Woodlawn-Mount Vernon area in 1845 for two reason: the availability of hardwood timber to be used in New England shipyards, and the eschewance of slave labor in the area. The Snowdens divided the acreage, then known as Wellington, into three sections. Isaac Snowden and his wife lived in the house that still stands at River Farm.
In 1866, 280 acres including the present-day River Farm were sold to three men known as “The Syndicate.” A writer from The Washington Sunday Star visited the estate in 1904 and referred to it as “this broken and pathetic house.” The Wellington property was subsequently purchased in 1912 by Miss Theresa Thompson, a member of a prominent local family that owned and operated Thompson’s Dairy, a business concern active in the area until the 1960s. Miss Thompson made changes and improvements at Wellington, but it was Malcolm Matheson, who bought the property in 1919, who transformed it into the charming early-20th century country estate it is today. The evocative 18th century-style paneling in the ground floor rooms, the welcoming foyer, and the light-filled ballroom were all part of Mr. Matheson’s reconstruction of the house. Out-of-doors he cleared acres of honeysuckle, briar, and blackberry to plant boxwood, magnolia, wisteria, and other ornamentals to create a serene park-like setting for his family.
Wellington faced one more upheaval. In 1971, Mr. Matheson decided to sell his home, and the Soviet Embassy offered to buy the property for use as a retreat or dacha for its staff. In the lingering Cold War, many people, locally and across the country, objected to the thought of George Washington’s farm becoming the possession of the Soviet Union. As a result, Congress and the Department of State asked Mr. Matheson to withdraw the property from the market.
Among those concerned by the potential sale was Enid Annenberg Haupt, philanthropist, gardener, and member of the Board of Directors of the American Horticultural Society. Through her exceeding generosity, the Society was able to purchase the 27 acres then comprising the Wellington estate, agreeing to keep the property open for the enjoyment of the American people. In honor of George Washington, one of our nation’s first great gardeners and horticulturists, the property was again named River Farm. In 1973, AHS moved its headquarters from the city of Alexandria to River Farm. First Lady Patricia Nixon joined Mrs. Haupt at the dedication of the property and together planted a ceremonial dogwood tree in the garden.