Most of what you buy at a road side stand is actually " grown-in-California, -Mexico, -Peru or wherever produce".
That far north the produce does not really come in until the mid to late summer. Which is not when people are buying. They want to buy "farm fresh vegetables" in the spring.
Same thing at the farmer's market. If it seems a bit early for what you are seeing it was trucked in.
we have the farmers’ market from late May to October...all grown on local farms in New Jersey; starting with radishes and asparagus, then blue berries and mulberries, then the regular summer fair like the best jersey tomatoes, watermelon, potatoes, peaches, beets, kohlrabi, apples then cabbage and cauliflower.
But most city folks don’t know what time it is let alone whether its early. Its always available in the store so it must be the right season. Farmers just make that stuff the ripe way. Its kinda like how meat doesn’t come from animals, it comes from the grocery store.