For future reference, cartridge case Id can come from headstamps if enough info is there, and if not, case mouth diameter, and case length are important.
Case 2nd from left is a U.S. 75mm M18 most likely Sherman Tank gun case. The middle case appears to be a Canadian manufactured 3.7 inch antiaircraft gun case. 4th from the left is an Italian 75mm case, and the case on the far right is French, in the 75mm range.
All this being said, case lengths are still needed to make sure the cases haven't been cut short to be trench art or blanks. Photos of the sides of the cases with length measurements and case mouth diameters would be very valuable for final ID confirmation.