Well it could also mean parched corn, a staple of the poor in the South, white and black. Something like half-popped popcorn.
So I interpret that song to mean - 'long as I got somethin' to eat, I don't care where da Massa gone to.
[link|http://www.shepherd-express.com/shepherd/19/44/news_and_views/straight_dope.html|http://www.shepherd-...traight_dope.html]
When I was young a us'd to wait
On Massa and hand him de plate;
Pass down the bottle when he git dry,
And bresh away de blue tail fly.
CHORUS
Jim crack corn I don't care,
Jim crack corn I don't care,
Jim crack corn I don't care,
Old Massa gone away.
Den arter dinner massa sleep,
He bid dis niggar vigil keep;
An' when he gwine to shut his eye,
He tell me watch de blue tail fly.
CHORUS
An' when he ride in de arternoon,
I foiler wid a hickory broom;
De poney being berry shy,
When bitten by de blue tail fly.
CHORUS
One day he rode aroun' de farm,
De flies so numerous dey did swarm;
One chance to bite 'im on the thigh,
De debble take dat blu tail fly.
CHORUS
De poney run, he jump an' pitch,
An' tumble massa in de ditch;
He died, an' de jury wonder'd why
De verdic was de blue tail fly.
CHORUS
Dey laid 'im under a 'simmon tree,
His epitaph am dar to see:
'Beneath did stone I'm forced to lie,
All by means ob de blue tail fly.'
CHORUS
Ole massa gone, now let 'im rest,
Dey say all tings am for the best;
I nebber forget till de day I die,
Ole massa an' dat blue tail fly.