While going through some old e-mail, I found a list of tombstone abbreviations that our editor Maggie Rail sent me several years ago:

AF&AM - (masonic)
AOF - Ancient Order Of Foresters
AOH - Ancient Order Of Hibernians
AOKMC - Ancient Order Of Knights of Mystic Chain
AOUW - Ancient Order Of United Workmen
ALOH - American Legion of Honor
AUM - Ancient Order of Mysteries- Masonic Order
BPOE - Benevolent and Protective Order of Elks
BPOEW - Benevolent and Protective Order of Elks of theWorld
CK of A - Catholic Knights of America
COOF - Catholic Order of Foresters
CTAS - Catholic Total Abstinence Society
CBKA - Commander Benevolent Knights Association
CCTAS - Crusaders-Catholic Total Abstinence Society
CSA - Confeserate States of America
DAR - Daughters of American Revolution
EBA - Emerald Beneficial Association
FAA - Free and Accepted Americans
F&AM - Free and Accepted Masons.
FOE - Fraternal Order of Eagles
GALSTPTR - German American Legion of St. Peter
GAR - Grand Army of the Republic
GLAUM - Grand Lodge Ancient Order of Mysteries-Masonic Order
GUOOF - Grand United Order of Odd Fellows
IHSV - Red Cross of Constantine
IOI - Independent Order of Immaculates
IOKP - Independent Order of Knights of Pythias
IOOF - Independent Order of Odd Fellows
ISH - Independent Sons of Honor
IORM - Improved Order of Redmen
IWW - Industrial Workers of the World
JAOUW - Junior Order-Ancient Order of United Workmen
JOUAM - Junior Order-Order of United American Mechanics
KGL - Knight Grand Legion
KM - Knights Militant
KC - Knights of Columbus
K of C - Knights of Columbus
K of FM - Knights of Father Matthew
KFM - Knights of Father Matthew
K of H - Knights of Honor
K of L - Knights of Loyola
K M - Knights of Malta (Masonic)
KMC - Knights of the Mystic Chain
KPC - Knights of Peter Claver
KP - Knights of Pythias
K of P - Knights of Pythias
KSC - Knights of St. Columbkille
KG - Knights of St. George
KSTG - Knights of St. George
KSTI - Knights of St. Ignatius
K of SJ - Knights of St. John
KSTJ - Knights of St. Joseph
KSL - Knights of St. Lawrence
KSTM - Knights of St. Martin
K of STP - Knights of St. Patrick
KSTP - Knights of St. Paul
KSTP - Knights of St. Peter
KSTT - Knights of St. Thomas
K of STW - Knights of St. Wenceslas
KT - Knights of Tabor
K of T - Knights of Tabor
KWM - Knights of Wise Men
KGE - Knights of Golden Eagle
KHC - Knights of Holy Cross
KKK - Knights of Klu-Klux Klan
KOTM - Knights of Macabees
KSF - Knights of Sherwood Forest
KT - Knights Templars (Masonic)
LAOH - Ladies Ancient Order of Hibernians
LK of A - Loyal Knights of America
LOM - Loyal Order of the M.O.O.S.E.
MOLLUS - Military Order of the Loyal Legion of the United States
MRA - Royal Arcanum
MWA - Modern Woodsmen of America
NOK - New Order Knights (see KKK)
OES - Order of the Eastern Star
OUAM - Order of United American Mechanics
PM - Patriarchs Militant (Independent Order of Odd Fellows)
POSA - Patriotic Order of the Sons of America
RMOKHSJ - The Religious and Military Order of Knights of the Holy Sepulchre
of Jerusalem
RSTV - Rite of St. Vaclara
RSTV - Rite of ST. Vita
RK - Roman Knights
SR - Scottish Rite (Masonic Order)
RAM - Royal Arch Masons
RO-AUM - Rosicrucian Order (Masonic)
SBCL - Saint Bonifazius Catholic Union
SBL - Society B. Lafayette
SCV - Sons of the Confederate Veterans
SAR - Sons of the American Revolution
SNA-AUM - Shrine of North America (Masonic)
SV - Sons of Veterans
TH - Temple of Honor-Independent Order of Odd Fellows
UCV - United Confederate Veterans
UDC - United Daughters of the Confederacy
VFW - Veterans of Foreign Wars
WOW - Woodsmen of the World

I have one other abbrevation to add to the above:

RIP - Rest in Peace