Grits: singular or plural?

[sagehen]

 - Jim Landau writes:
>For Lois McMaster Bujold fans, "groats" is also a mass noun.  According to
>MWCD10, groats are ground coarser than grits and are not necessarily from
>hominy.
~~~~~~
I think "groats" usually refers to hulled, but not ground, grains, as in
buckwheat groats  or oat groats.
I sometimes wonder about the countability of "grounds," when I get one
particle of ground coffee caught in a tooth!
A. Murie