Cram's presentation is a parody of Spam, down to the same style of packaging and font. Prior to Fallout 4, it was shown to come in a cardboard box, instead of Spam's signature tin can. In Fallout 4, its container was changed to a tin can.
The name cram itself is likely a reference to the biscuit-like food made by the humans of Lake-town and Dale in The Hobbit and The Lord of the Rings. Unlike Fallout's Cram, it was made with tightly pressed flour or meal.