Mary Marvin Breckinridge Patterson, granddaughter of B.F. Goodrich and widow of an heir to the National Cash Register fortune, wants to give her elegant waterfront farm to the people of Maryland, "but only if they want it," she said. And therein lies a catch.

The gift of architect-designed Point Farm in Calvert County is in honor of her late husband, Jefferson Patterson, who built it in the 1930s. It is a place of rare appeal, so rich in history that when archeologists quickly surveyed one-fourth of it they found 46 significant sites, including 36 prehistoric Indian sites dating to 7600 B.C. and fossils 12 to 14 million years old.

"All we could say was, 'Wow,' " said Wayne Clark, the state's administrator of archeology, who believes that when the land is fully excavated 120 important archeological sites may be unearthed.

Whether he will get to dig again, however, and whether Marylanders will get to wander Point Farm's rolling fields and miles of Patuxent River shoreline, is up to elected officials. Patterson, 77, wants the state to show good intentions by approving a healthy operating budget for the Jefferson Patterson historical park before she turns over the keys.

On the advice of the Maryland Historical Trust, Gov. Harry Hughes proposed $400,000 to get the park going next year, two-thirds of it for capital improvements, the rest for staff. That suits the donor, but there are signs in these tight fiscal times that legislators want to chop the figure.

State Sen. Bernie Fowler (D-St. Mary's), who heads a subcommittee working on the donation, said he understands Patterson is more concerned with "signals of the state's intentions" than hard dollar figures. "I don't think we'll be bound up over whether it's $300,000 or $398,000," he said.

On the contrary, Patterson said quite specifically last week, "If they're not going to fund it, I'm not going to give it to them . . . . I'll give it to someone else. I don't give things away if people don't want them."

It is in the nature of elected officials to compromise. Perhaps in their wisdom legislators will succeed in compromising with Patterson. It might help them to know a little about her, lest they be tempted to trifle.

Patterson rode horseback into Appalachia in 1930 to make the film, "The Forgotten Frontier," about nursing and midwifery in the Kentucky mountains.

She was an avid polo player and the first woman pilot in Maine. She published a book of photographs from a voyage to primitive Africa in the 1930s and broadcast news reports from war-torn Europe.

She was married in Berlin during World War II and, with her husband, a career diplomat, lived in Peru, Belgium, Egypt, Greece and Uruguay, all the while maintaining Point Farm and homes in Washington and York, Maine.

It might help legislators to know she was twice burned in land donations. She gave 45 acres in Maine to York Selectmen, who let the land and a house go to waste; her husband donated his family mansion in Dayton, Ohio, 29 years ago and just last year city fathers said they were no longer willing to pay upkeep.

"It's hard to give things away," sighed Patterson, extracting a filtered cigarette from a silver case.

The fear that Maryland will somehow fritter away its chance at an archeological, paleontological, environmental and cultural Valhalla worries Clark.

Last week he led a quick hike across one unsurveyed Point Farm field and in half an hour found six new historical sites rich in prehistoric Indian artifacts or 17th century pottery and brick. He and archeologist Mike Smolek were like children in a toy factory, coursing along the field plotting centuries-old house sites by shards of brick and oyster shells in the ground.

"In 19 years of archeology in Maryland, I found one complete Indian hatchet," said Clark. "In one week here I found three."

The beauty of Point Farm, he said, is the record it holds of continuous habitation by man for perhaps 12,000 years. Its location at the juncture of the Patuxent and St. Leonard's Creek, the river's biggest tributary, made it an appealing hunting and fishing spot for Indians and European settlers alike.

Capt. John Smith discovered an Indian town there in 1608; by 1640 it was St. Leonard's, one of Maryland's first towns.

Now, if the state agrees to terms, it will be a park. The farm also would house new offices of the Philadelphia Academy of Science's estuarine laboratory and would have links to nearby Calvert Marine Museum and the University of Maryland's Center for Environmental and Estuarine Studies in Solomons.

There is talk of establishing a scientific headquarters for research into estuaries, similar to the Woods Hole marine research laboratories in Massachusetts.

Beyond that, state acceptance of the land and buildings would give ordinary people access to an ageless river and a working Southern Maryland farm in postcard-perfect condition, right down to the copper guttering on the brick carriage house and the oak paneling in the show barn.

"The important thing," said Patterson firmly, "is to go ahead and get it going. I want to make sure it's a good show."