Rural Plains. Possibly the oldest in the country to be inhabited continuously by the same family, this 318-year-old house has been home to nine generations of Sheltons

A CANNONBALL rests quietly on the hearth in the Sheltons' parlor, near a square Steinway piano once owned by Dolly Madison. Upstairs, a guest room is furnished with a solid mahogany four-poster bed brought from England in 1632. On the back porch, a leather Revolutionary War helmet stands sentinel over a wooden canteen still redolent of cedar. A bowlful of Civil War bullets, picked up around the yard and fields over the last 100 years, is displayed in a glass-fronted case.

``They've just been handed down from generation to generation,'' says William Shelton of the astonishing historical relics that fill his 318-year-old home. ``Some of them I know about and some of them I don't.''

Possibly the oldest house in the country inhabited continuously by the same family, Rural Plains, seven miles north of Richmond, is not a museum or historical re-creation. It has simply been the residence of nine generations of Sheltons, consummate collectors of the tangible items that make history seem real.

Strangers touring the historical sites of the area occasionally stop and ask to see the two-story, brick, colonial-Dutch house built in 1670. William and Hollie Shelton say they have never charged admission, as some of the grander plantation houses do.

But every one of Rural Plains's 13 rooms is a testimony to history.

THE Sheltons point out the memorabilia of past centuries casually, the way other families show old snapshots. Beneath the dining-room chandelier is a mahogany drop-leaf table that has been in the family 200 years. A vase of roses rests on a little 18th-century duck-foot table in the parlor. The cast-iron box lock securing the wide, maple parlor door has probably served for three centuries.

A gleaming dress sword that belonged to Edward Shelton, a colonel in the Confederate Army, hangs over the living room fireplace. A Civil War pistol, a bit rusty, is on the porch.

Items from different centuries are placed side by side, like an old grandfather visiting with children. An Indian arrowhead, older than even the house, rests among the Civil War bullets. Near a Civil War officer's tasseled epaulets is a pair of World War I army boots that belonged to Mr. Shelton's uncle.

The house itself, its brick walls a foot-and-a-half thick, attests to the skill of its builders, many of whom were probably slaves.

``There are very few nails in the house,'' observes Shelton, who marvels at the great roof beams visible in the attic. ``All the rafters and peak of the roof are put together with wooden pegs.''

HANOVER County records were destroyed by fire after the Civil War, but a number of outstanding events in the life of the house are known. As its contents affirm, Rural Plains has witnessed dramatic periods of history, as well as the private celebrations and sorrows of the family who lived here.

Built in the days when much of Virginia was wilderness, the house was originally the seat of the 5,000-acre plantation of John Shelton, who received a land grant from the British crown.

In 1754, at a youthful 80 years old, the house was the scene of a famous wedding. Patrick Henry married Sarah Shelton before the pine mantle in the front parlor. The couple received 300 acres of Shelton land as a wedding present.

A century later, the house took blows in the war of brother against brother. While Col. Edward Shelton was away with the Confederate Army, Union Gen. Winfield S. Hancock made the building his headquarters, confining Sarah Oliver Shelton and her children to the basement.

In one day of shelling, Confederate troops struck the walls of the house with some 40 cannonballs and riddled the cypress-shingled roof with bullets. But the solid structure stood intact.

The house is certifiably old now, listed on the National Register of Historic Places and the Virginia Farm Bureau Bicentennial Farm Register.

All but 125 of the original 5,000 acres have been divided among family members over the centuries or expropriated for delinquent taxes after the Civil War. But none of the original property was ever sold.

The house does not even have a deed.

WILLIAM SHELTON once lived in California for six months, back in 1954. But then his father became sick, and he returned home. ``I loved the climate out there,'' recalls the tanned, 68-year-old man, who operates a nursery on former plantation land.

Starting in 1961, he lived in Richmond for three years after his marriage to Hollie Enroughty. But when her youngest son finished high school, the couple moved out to Rural Plains, where they have stayed ever since.

Some might find it trying to live in the long shadow of the past. But the Sheltons coexist with history as easily as do the giant old elms that shade their cool front lawn.

``Honey, we live in this house,'' says Mrs. Shelton, noting that family gatherings are held here, and her book club meets in the parlor where Patrick Henry was married. ``I do all the work myself,'' she adds, ``without a bit of help.''

``It's hard to work with an old house, to make it comfortable,'' she confides, explaining that she grew up in Jarrett, Va., in a house inhabited for merely a century.

Dampness, especially in the basement, is a continual problem. Repairs are perpetually needed. A few decades ago, Mr. Shelton had to replace most of the hard pine floorboards downstairs.

They have made a few modernizations. The kitchen cabinets, eight years old, are the newest things in the house. Behind the wide old kitchen door with its HL hinges are a refrigerator, stove, and sink. The bathrooms are modern. Mrs. Shelton has hung wallpaper in the stairwell.

A bright new American flag is mounted by the front door near initials said to have been carved in the brick by Union soldiers camped in the house during the war.

``History has been instilled in me all my life, I guess,'' says Mr. Shelton. But he adds that the true family historian was his sister, Mary Winn Shelton. A member of the Sovereign Colonial Society of Americans of Royal Descent and the Daughters of the American Revolution, she charted family history, kept files, and unearthed records.

It was she who hung in the front hall of the house the family coat of arms, near a four-foot-tall pen-and-ink diagram tracing the Shelton line back to England, past Anne Boleyn, to the 13th century.

Upon her death in 1967, a local newspaper noted that she had written to correct every historically inaccurate statement that made it into print.

SHELTON, a farmer who went into the nursery business with his father, has divided his time between preserving antiquities and nurturing new growth. Today he is tending 3,000 young English boxwood, white pine, and holly in the fields around the house.

A neatly groomed man with a plain-spoken manner, he refers to the house as ``sacred,'' and shudders at the thought of letting it go on the market. ``I've always been very proud of it because of the respect I have for my forefathers throughout the ages,'' he says.

``We have Sheltons come here from all over the United States, trying to trace their family line,'' he continues.

But he is the only remaining member of the direct line of Sheltons who have lived in the house for three centuries. He has no children. And none of his cousins, he says, have any interest in owning Rural Plains.

His first cousins live at Studley, birthplace of Patrick Henry. Other relatives are throughout the country.

Shelton says he has willed the house with 10 acres to a Virginia preservation society. ``It's the only way I think it'll be preserved.'' With his passing, the long history of the Shelton family in the house will come to an end.

But with reasonable care, Shelton believes, the house itself could last indefinitely.