You can't buy Turkey Produce in the General Store.
You are talking about this quest:
Fire heart (Turkey)
Waupee (White Hawk): The next ingredient is the heart of a turkey. Don't worry, you don't have to gut it. Just bring me a turkey. Henry can take out the heart and sell the rest as dinner.
Target: Hunt a turkey.
Requires:
Turkey 1/1 (Done)
Reward: + 30 Experience points
To complete the quest you need to do this job:
Hunting turkey
A turkey walks almost into you. You should be able to find a lot in the forest.