That's how interepreted the question, too.
@SilverShutter I think if you ask nicely, there are people on this forum who would be happy to send you a scan of some of their 'natural borders' so you can use these for your own photographs. Use a transform tool and a layer mask in your favorite photo editor to use such a border as an overlay. There are also Instagram filters for this kind of thing. Mind you, I never find the results very convincing and much of the time it's being applied in a way that makes the result look tacky and fake, so I'd practice restraint in using an approach like this.