I think lettuce is my most useful crop. We've been eating it nearly every dinner for a month now. It tends to bolt, so I plant it thick and just harvest the tallest plants to make room for the smaller ones. I think this variety is called Buttercrunch Bibb. I keep planting more lettuce seeds every few weeks, when I see some spaces where it might fit. I have two nice mixes with endive that I am planting now. I have read that I can keep planting lettuce through August.