I believe the culprit here is either a fall blooming Crocus or something called a Colchicum, which mostly bloom in the fall time and sporadically afterwards, sometimes into spring. They either produce nectar or a bright orange pollen, passably black. Other then that the only thing I can think of is someone's greenhouse with one of the sky lights (if you can call it that in a greenhouse) left open. There is one near me that I can think of in the Cherryhill and I suspect the owners to be beekeepers because they have some great bee plants there. And even some of the stranger ones like Pansies I see bees on at their store. Every time I go there I see bees absolutely covering some plant of theirs, and it's usually a strange thing like a Mum, I'll buy it and bring it home and my bees won't touch the dam thing. Had great success with their dark Sedum though.
Any who, fleshy plants such as Crocus, Tulips, Alliums, basically bulbs and corms, tend to all come from colder climates and easily grow during colder times of the year. Thought they usually only bloom once it's above 50F when pollinators are active.