It is by far the most popular plant I've helped people to grow. All children love it. OK I'm exaggerating, but only slightly. If you've never tasted sorrel it has a sharp, citrus tang to the leaves and children love eating it straight off the plant.
It's also really tough, grows back every year and you can easily take cuttings from it by slicing off a part of the root using a sharp spade. This is best done in spring. Simply replant the part you cut off and in a few weeks you'll have new leaves growing.