We could not locate a commemorative plaque for the Mokelumne Hill IOOF Hall. Here's a list of other California Historical Landmarks which had no bear flag plaque when we visited them.

The Independent Order of Odd Fellows (I.O.O.F.) is an altruistic fraternal organization derived from the similar English Oddfellows service organizations which came into being during the 1700s....Although in Britain the Odd Fellows tended to meet in pubs, in the U.S. the lodges often built their own facilities. Many of these are now on the U.S. National Register of Historic Places....

From Wikipedia entry for Independent Order of Odd Fellows