I stopped to check this one out because for a moment I thought it was a style of O & M stamp I hadn’t seen before, and I have been trying to catalogue all those variations. Instead I found a stamp from the mysterious G & M, on the east side of Foster Avenue between Prospect and Michigan.
I haven’t been able to find out much about G & M. I am guessing they were the G & M Construction Corporation, which I can find an entry for in OpenCorporates. They incorporated in June 1995 and dissolved in 2003.
Assuming this is the same G & M Construction Corporation, they were located on Pollard Road in southwest Lansing at an address that seems to just serve as a house today.