There were two companies from Butler County by that name. Here's a copy of the Governor's commissions to the first company:

Greenville Guards

Executive Department
Montgomery Ala. May 3, 1861

The Secty of State will issue commissions to

H. A. Herbert Capt.
J. J. Deens 1st Lieut.
L. A. Livingston 2nd Lieut.
David McKee 3nd Lt.

Of the “Greenville Guards”

Butler County Ala.
A. B. Moore

[commissions issued from same date; effective May 1, 1861]