Italian Tax Stamp

Sorry to revive an old thread but better than starting a new one I figure since the picture is already there!

I have three of these, the 5L, 20L, 50L, and a 30L in a slightly different design. All in F-VF and cancelled. Do these stamps have any value?

I also have several other oddities, including quite a number of Revenue's (Marca Da Bollo).

The other oddball is a square grey stamp, 20L, that says "G. Ricordi - C. Editori - Milano" and "Avmento Compreso". Any ideas?

Thanks!