I've been digging for maggots and skippers, working on that verse as well. No buttermilk, but these:

Milk in the dairy getting mighty old,
Skippers and the mice working mighty bold,
Sing song Kitty can't yer kinny meo
Keymo ki mo doro hi me hi me ho.
In come Sally singing, sometimes
Penny with a wink turnings cat
Sing song Kitty can't yer ki meo
Key mo ki mo doro hi, me hi me ho.

Obviously descended from the song "Kemo Kimo." Collected in 1915, "sung by an ex-slave." N. I. White, American Negro Folk-Songs, 1928 (1965 reprint by Folklore Associates), p. 176.

I went up to town to get a cake of cheese,
The skippers and the maggots and a long-tailed mouse,
Yonder come a nigger with a bucket full o' souse,
Just come down from the white folk's house.

Collected 1915-1916, Auburn, AL, heard in southern Alabama.
Also in White, p. 176.
Kemo Kimo is an old English nonsense rhyme, but it got a workout in minstrel shows in mid-19th century and later and passed into Negro folk songs.
A variant of the first occurs in "Git Along John," Negro Singers' Own Book, 1846(?). Mentioned in White, p. 175. A similar verse was reported by Odum, also mentioned in White.

The buzzards and the hawks appear in a number of old Negro rhymes and tales. One in Tally (collected in the 1920s):
Once: De hawk an' de buzzard went to roost,
An' de hawk got up wid a broke off tooth.
Den: De hawk an' de buzzard went to law,
An' de hawk came back wid a broke up jaw
Dat buzzard tried to plead his case,
Den he went home wid a smashed in face.
Talley, Negro Folk Rhymes.