In most of our environments, I think we realize that many garden seeds just would not survive scattered about and left through the winter. Still, it probably needs only a little help and protection.
I'm somewhat surprised when anything survives a winter and volunteers! Think about early agriculturalists. Isn't it surprising that Native Americans had gardens into what is now southern Canada and the Dakotas?
I don't know how much they contributed to their diet, probably a lot or gardens wouldn't be worth the bother. Still, there are lots of us "beyond the pale." I wonder about the Euro-American immigrants here. Did they even have a variety of corn they could grow here in the 1800's? Wheat? Sure, but I don't think they had any sweet corn ... how did they survive?!
Made of stern stuff those folks were. Especially since they lacked the skills of the Natives who had been here for millennia! Lettuce think on the qualities of both ....