I agree that they would need to be balanced in some way. Potatoes could be added as 1.) True potato seeds, as in from the potato berries. Yielding wildly varying results and giving different types of potatoes such as; An inedible "small weird potato", a "medium" potato on par with mushrooms and other crops, and then a heartier potato offering more satiation.
and
2.) "Seed" potatoes as in just planting the potatoes themselves guaranteeing you get the same potato you planted.
This would mean that to keep getting the potatoes you wanted you would need to keep some potatoes from rotting during winter.
This allows a "challenge" for people not playing with story elements in their game, while also allowing heartier potatoes to become a trade item from agricultural traders or a possible story element/Reward Similar to the elk.