I bought a bag of baby leaf salad leaves from Tesco today. I was tucking in when I came across some Shepherd's Purse (Capsella bursa-pastoris). I thought it was a mistake as it's a common field weed but I just checked online and it is edible. Rather nice too - flowers, seeds and all. It's full of vitamins apparently and the Romans grew it as a pot herb. It has a long history of use to treat haemorrhages...which could be handy as it's a Friday night!