I read in a book (years ago) that the shortnin' bread was the main intagonist. In the early century, shortnin bread killed the poor black familys that consumed it and as often than not, kids made fun in song.

Mammies lil baba
Loves shortnin, shortnin
Mammies lil baba
Loves shortnin bread

Two lil chillun lyin'in bed
One rolled over 'n'
tha otha' one's dead!

It was the shortnin bread itself that killed the children because they loved to eat it and it was bad for them. (Lead poisoning?).

Maybe it's not lid in the lyrics but rather "lead" pronouced as "lid".