What with so many varieties of lettuces, kales, chards and spring salad favorites where should you begin with your spring greens seed choices? Garden greens are some of the most nutrient-dense plants for your health, packed with cancer fighting folates. Lettuces are also primarily self-pollinating, making them an easy choice for seed saving for future garden seasons. Lastly, they naturally filter water from the ground, providing a clean food source of hydration for emergency situations.