Who ate with the pilgrims on Thanksgiving?

There are two written accounts of the Plymouth colonists' harvest feast in 1621: one from Edward Winslow (published as "Mourt's Relation") and the other by William Bradford ("Of Plymouth Plantation"). Both mention that the colonists prepared numerous waterfowl--presumably, ducks and geese--and that the Wampanoag Indians brought five deer. Bradford's account also mentions wild turkeys. That is all we know from the first-hand accounts of the feast itself.

It is likely that fish and shellfish were served, also, as those were a staple of the colonists' diet. During the fall, a considerable amount of fish was being smoked, salted and stored in preparation for winter.

"Indian corn" (maize) was the primary crop whose harvest was being celebrated. The hard, colorful corn was ground into a porridge and cooked. It is possible that some of it was cooked as a flatbread. Vegetables would have included cabbage, beans, onion and squash. They had brought seed for wheat and peas from England, but those crops had failed.

The colonists routinely foraged for edible plants. It is likely that they ate native berries, grapes and plums, but not Apples. The only Apples in North America were crabApples, which were unpalatable. Cranberry sauce had not been invented.

In 1621, the colonists did not have ovens and their sugar supply was almost gone, so they would not have had pies or desserts.

See links below for background info.
Turkey!