Many contractors made haversacks for the Confederacy. Some used buttons and some used buckles to fasten the flap. Buttons seem to be more common for CS haversacks. Material and pattern varied among contractors but they were all approximately the same size and used to carry rations. Haversacks became unbelivably greasy and dirty during use. There was no need to mark them with individual markings. The owner could tell his own by the smell. (just kidding) The Musuem of the Confederacy as well as Gettysburg NPS each have at least one CS haversack in their collections. One is made from a tarred cotton material with a button fastner and the one in GB NPS is a white, uncoated cotton material secured with a bone button. If you do a goggle search for civil war haversacks you will come up with lots of vendors selling reproductions. I would suggest you look at the confederate haversacks here:
Each one is patterned off of an original in a collection.