Empty plot over the winter - to cover or not

Is there a green manure that dies before spring, doesn't seed itself and doesn't need to be dug in?

Winter purslane, AKA miners lettuce or claytonia.

Starts to germinate and grow now, will give you green salad leaves all winter, and by March has pretty much died away. It will seed itself, but that's not a problem because it won't germinate and start to grow again till next autumn.  

It is a small, low growing annual plant so you need a lot of seeds to cover a big patch.