The wild Blackthorn, Prunus spinosa, is in flower in all our hedgerows at this time. I think that it is as good as any garden shrub, and you get the sloe berries too in early winter.
There is a legend that its flowering always comes at the time of a late cold spell, called the Blackthorn Winter. That is certainly true this year, since we have had some really hard frosts every night this last two weeks, more than all winter which was exceptionally mild. I have been running around trying to cover things up in the garden, but some things still got caught, like this collapsing Arum found this morning.