About the time they eat their first slice of turkey and sniff the aroma of pumpkin pie Thursday a few Virginians will be giving less than heartfelt thanks for the landing of the Mayflower at Plymouth, Mass., more than 350 years ago.

It was the landing at Plymouth and its successful pilgrim settlement that Thanksgiving is commonly associated with. But it upstaged what some Virginians contend was the first official Thanksgiving, a religious service at Berkeley Plantation, about halfway between here and Richmond.

The rivalry between Massachusetts and Virginia over whose pioneers started Thanksgiving has continued off and on for more than 20 years. Virginia's claim is considered a joke in Massachusetts. But in Virginia, it's serious.

To add to the insult, James Deetz, a visiting antrapology professor at the College of William and Mary, said that indeed Thanksgiving as we known it today originated with the Plymouth pilgrims. The Berkeley settlers may have been the first to declare an official Thanksgiving in honor of their safe journey to the New World, but it was religious, lasted only a few minutes, was not fun and had not games, he said.

"Heck, they (Virginia) got the first colony, the British surrendered at Yorktown and they (Virginia) have more presidents," joked Deetz, a professor at Brown University in Rhode island who also works at the Plimoth (Mass.) Plantation museum. "They could at least let us have the first Thanksgiving," he said.

Most people think a real Thanksgiving "must include Indians, corn, turkeys, pilgrims with buckles on their hats, which they actually never had, games, eating a lot of food and celebrating the fact that it's been a bountiful year," provisions that Deetz said the Virginia celebration did not have.

But to some Virginians, Thanksgiving was first declared on Dec. 4, 1619, two years before the Plymouth celebration. To gain recognition for the achievement, some Virginians established the Virginian Thanksgiving Festival, Inc. in 1958. Each year the group has an annual Thanksgiving drama, music and guest speaker, usually in November but not when the rest of the country celebrates Thanksgiving.

Both sides in the dispute say they have documentation for their versions of history. But the Plimoth Plantations spokeswoman said she had never heard of Berkeley or Virginia's rendition of the facts.

"It's not silly if you want to keep your American history honest," said Malcolm Jamieson, Berkeley's owner and a member of the festival's board of directors. "If you made a mistake, admit you made a mistake," Jamieson said of the Plymouth people.

Virginia's claim was not fostered until the last 20 years because "we just didn't want to make such a big publicity stunt," about the celebration, Jamieson said.

For example, the Berkeley owner said, "a man in Virginia did better stuff than Paul Revere.But Virginia just didn't publish its history."

Jamieson said the Virginia effort has been successful in changing Thanksgiving history in some textbooks in the state and in 1962 President John F. Kennedy even acknowledged that Virginia had the first declared Thanksgiving.

IT is not clear how Thanksgiving became associated with the Plymouth settlement, especially since such harvest festivals were held by many colonies at different times before winter.

Judith Ingram, spokesman for the Plimoth Plantation, whose name is spelled in the colonial way, said that the connection was probably "a peculair quirk in history."

Before the first American Thanksgiving was declared in 1789 by George Washington, Thanksgiving were celebrated independently by communities. Washington's declaration went largely ignored.

Then Abraham Lincoln, during the Civil War, called for a yearly Thanksgiving day to be celebrated during the last week of November.

Before the 1900s the word pilgrim was largely associated with early American settlers, Ingram said, but winters and illustrators began depicting pilgrims as landing at Plymouth Rock.

At the beginning of the 20th century, people began associating pilgrims and Thanksgiving and therefore Plymouth with the holiday, Ingram said.

Plymouth's popularity probably also stemmed from its success as a settlement, Ingram said. In contrast, all 500 Berkeley inhabitants were killed in 1623 by an Indian raid, Jamieson said.

In 1931, papers documenting the Berkely observance were found in a New York City Library by Dr. Lachlan Tyler, a descendant of the 10th U.S. President, John Tyler, Jamieson said. The library had purchased the letters in 1898, but they did not become wellknown because "nobody cared about it then," Jamieson said.

According to the documents, the land at Berkeley was part of a grant by King James I. When the 39 settlers of the English ship Margaret stepped beneath the poplars and willows on the James River shore of what would become the plantation, they immediately knelt and gave thanks to God for their safe journey.