wt1,
I found several of that stamp listed at
www.ericjackson.com in the State revenues section -- he lists it as:
SOUTH CAROLINA STATE REVENUES
Business License Tax Stamps
SRS #SC BL37S
3c chocolate
Year: 1924-29
(And after two years at MCRD Parris Island I can tell you that the "palm tree" is really a Sabal Palmetto, the official state tree.

)
Steve