Chicken breeds with "fur"

[Mbean15]

I have a little gold and white barnyard mutt i got at a flock swap. The lady had no idea what they were when i bought them.
I have one girl I had to catch because I saw her underside was covered in big, black spots. To my surprise the spots were clumps of dirt tangled in soft, white, fur-like fluff, which makes up a majority of her underside. I think silkies are known for this, but are any other chicken types?
I think shes a RIR mix

 

[Mbean15]

 

[oldhenlikesdogs]

The feathers are like that on their underside. Looks like a red sex link called a comet, otherwise she's a mix.