We call that Novelty Siding, its pretty common here in the Northeast. I just redid my barn and had to piece in a lot of it, comes in 6 or 8 inch widths. Not available off the shelf everywhere, but I can find it at a few lumberyards nearby. Usually made from #2 pine. Don't know where you are, but I'd think that a decent yard could order some for you. If you order it, you should order some pieces wider then you need. Meaning if you need 6" wide, order some extra 8 " so you can saw it down to fit as its not as forgiving as clapboards when applying, just has a 1/2 inch lap which is not much.
Last edited by Frost; 12-19-2018 at 05:23 PM.