I have noticed this for the last few years here in West Virginia.  I believe
it's corn dust or pollen they find aroound as it's the same color as the
pollen baskets on the bees I've noticed rolling around in the laying mash
and corn I give the chickens.  I live in an area where a lot of people keep
beef cattle over the winter and feed corn.
 
->For the past 3 or 4 warm days my bees have been coming in with there
pollen
>sacks so full that they seem very heavy when they land.  It is a dull gray
>colour.  I no of nothing in Ky that is blooming.