This year we planted Canola as a winter cover crop. Supposedly it has a long tap root that breaks up clay soil. I think we probably sowed it a bit too thickly for it to function that way but it is crowding out the weeds (which are thriving in our unseasonably warm winter weather) and gives the garden something nice and green to perk up the dreariness. This particular seed we got from Gardens Alive.
In other news, our invasive mint found a wonderful place to spend the winter: in the coldframe! You can see Lexy sniffing it out.