Compounds
From Sereer wiki
Noun-Noun Compounds
o fep maalo
grain of rice (lit. piece of rice)
mbep maalo
grains of rice
mbep ngaaf
grain of millet
pep kaaf
grains of millet
oɓek suukar (ole)
(this) piece of sugar (sugar cube)
Notice that "grain" varies between ofep, mbep, and pep, seemingly agreeing with the type of consonant in the following noun. It is worth figuring out which noun is forcing agreement with which: as it stands, it looks like the measured substance forces noun class concord on the measure word.