My hayfield is full of what I call red clover. My bees work it for pollen but I think bumblebees are about all that can reach the nectar. My pastures have Ladino clover and they work it good.
I think the yellow clover is called sweet clover, it comes in yellow and white. It was too dry here this year for the Ladino to do any good.
I understand there is one race of bees that has a tongue long enough to work red clover, carnolians perhaps?