Interesting...
The farm wrench openings do not seem to cover every size, I was thinking general purpose (household) wrench maybe, but perhaps not. Openings are very rough, and not the same on both sides, I think they were cut before the wrench was bent into an s-shape. Openings are (+/-) 5/8 7/8 1-1/4,13/16,9/16
If the 9/16 and 13/16 are assumed to be really extra sloppy, you get
1/2,5/8,3/4,7/8,1-1/4 , almost a set...
>American Seating Co wrench
Interesting...
Do you suppose the weird opening is just a variation of a wingnut wrench?