the picture below shows a plate with the letters AF and they stand for "Agricoltura e Foreste". I don't know much about this plate and the only clue about it is that it's listed in some tables with all the codes of that time. It's uncertain the minister that had control over these plates or the differences from the Milizia Nazionale Forestale that had similar tasks in the same years.
The picture I took the detail of the plate from was snapped on October 1937 in Piazza San Lorenzo in Florence and if you want to see the full picture click qui.
The picture was snapped by "Foto Locchi" and pubblished on the newspaper "La Nazione": I want to thank Giuseppe very much for sending it to me.