That's my favourite weed, er, free crop!
I positively encourage it to fill up empty space in my veggie garden.
Here's a couple of photos I took last month - it's just starting to get past its best at this time of year where I live...
I always leave enough to seed and it's vigourous enough to grow up through the mulch. I let it form a nice filler between my 'real' veggie plants but have to remove some around the smaller ones before it swamps them.
I pluck the leaves off and put them in a bowl with some boiling water, which is enough cooking in my opinion. Then they get stirred into cooked rice for a quick salad at this time of year, when it's getting too hot to want to cook every day.