I was just coming here to ask about mine, I had similar issues trying to figure out what it's deal was.
Mine is a 120, marked the same
TRENTON
PATENT
SOLID WROUGHT
120
as pictured below
Curiously though, mind has an extra couple stamps on the "toes" of the feet, on the reverse, there are two 7s stamped at that location, pictured below
I felt pretty discouraged when I couldn't find the serial number, I was beginning to think it was counterfeit.
Just like yours, mine had a flat base, but handling holes on both front and rear, as well as underneath
Does anyone happen to know what these stamps mean? could it be a date code like 07/07? going by the dates stated earlier, it shouldnt be 1877, and I would find it hard to believe it's a serial number, being that it's limited to 2 digits