What Americans think they know about the history of Thanksgiving doesn’t always square with the truth.

For example, it is generally believed that in 1621, the Pilgrims invited Wampanoag Indians to a feast in Plymouth Colony to celebrate their first harvest, and a good time, with turkey and pumpkin pie, was had by all. Well, maybe, and maybe not.

Historians, including those at Plimoth Plantation, a living museum in Plymouth, Mass., say that they do know there was a feast that year shared by the colonists and Wampanoag Indians, and Squanto, who had learned English, served as translator. But the one historical account of the actual dinner says venison was served and some sort of fowl, but it doesn’t specifically mention turkey. Pumpkin was available, but it is not likely the colonists whipped up a pie. Furthermore, sweet potatoes were unknown to the colonists, and cranberries may have been served but not as a relish....