I was going to take one, really, but I forgot. And I've just peeled it, cut it up and put it in the oven to bake! Sorry!
I harvested some kumara a week ago. Kumara is what we call the orange-fleshed sweet potato (it's the Maori word). I chopped the end off a shop kumara last spring and popped it into my garden, and it has been happily growing ever since, without supplementary water. The kumara aren't totally ripe yet: apparently I should wait until the leaves yellow -- but I've dug up a few anyway.
We discovered that freshly-dug kumara doesn't have much taste, but leaving it to sit a week gives you the flavour you expect. If you want to store kumara for any length of time, there is a recommended curing process given here. I'm just going to leave the tubers in the ground until a week before I need them.
When I was a kid, sweet potatoes were always white. Kumara from New Zealand started making their appearance in the early 1980s, if I remember rightly. They became popular because they were cheap, less likely to have strings than the white kind, and stayed an attractive colour when cooked. Nowadays, there's also a purple-skinned white sweet potato. I think it's the best-tasting of the three: it's reminiscent of chestnuts, and I like the mealiness. But growing the kumara was easy.
The plant I grew is a pretty (if rampant) vine with heart-shaped leaves and mauve morning-glory flowers. Hardly surprising as the sweet potato is Ipomoea batatas, from the same family as morning glory flowers. Growing sweet potato would be a fun gardening project for a child in a mild climate.