Thanks for the information about Company B's flag. Oh, and do you happen to have the whole article
pertaining to the "Jackson Guards" flag presentation ceremony from the (The Atlanta Southern Confederacy newspaper of May 23, 1861) ? I would interested in knowing if it contains anything else on this company! i also found out that their uniform was also dark green with gold trim, large dark hat with plume

Here is a little bit of info. on the flag that i found on Google Book search:
Maybe you may want to use some of this in your book on Georgia Civil War flags.

"The Blessed Place of Freedom"
By Dean B. Martin

"The original flag of the Irish Company in the 19th Georgia was green with a harp and
shamrock"
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"Brave Men in Desperate Times"
By John McKay

"To their left was a unit with another strong Irish Connection, the 19th Georgia
Infantry, with its Irish-themed colors bearing Company B, "Jackson's Guards", then-commanded
by Irish born Capt. John P. Kelly."
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[article from The Wild Geese website]

'Undaunted Courage': The Irish at Fredericksburg

link to article;
http://www.thewildgeese.com/pages/fredpt2.html
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Link to photo of the 19th Georgia flag from the Georgia State Capital, donated by the
U.S. War Department in 1905
http://content.sos.state.ga.us/cdm4/item_viewer.php?CISOROOT=/flag&CISOPTR=101&CISOBOX=1&REC=1

Best Regards!
John