Sandy Cerenzia informs me that this is a group called "The YAHMO Club", and her guess is that it was a group of "buddies". The photo was taken at Brock's Monument, year unknown.
There are quite a few members of our family in this photo (the numbers in parentheses refer to the index picture below): Frank Harlach (6) is in the front row, furthest to the right, holding the guitar; Behind Frank, furthest to the right in the second row, is Willie Manquen (14); In the third row, third from the left, is John (Jean Michel) Manquen (17), and furthest on the right is John E. Manquen (22); and in the fourth row, second from the right, is Al Manquen (26).
Here's a full index, courtesy of Sandy Cerenzia:
If anyone has more information about this group, please let me know.