Edward Winslow's account details that "they went out and killed five deer" and mentions that "our governor sent four men on fowling" and that "they four, in one day, killed as much fowl as, with a little help beside, served the company almost a week." While it is possible that turkeys may have been killed, it is more likely that ducks or geese were the primary targets.
In addition, the crops grown by both settler and Native American would have graced that early thanksgiving dinner. Corn, squash, potatoes, yams, even wheat to make bread were, in all probability, shared and enjoyed.