[Griffins]

I don't think this set is any more obscure than the Goudey sets that preceeded it, but I don't think it's nearly as widely regarded as '33 or '34 (nor the '38 issue) and certainly not as collected.
The cards were issued in packs, a wrapper is below


Both SCP and Legendary have had point of purchase displays for this set in recent auctions, and uncut panels showing the entire back puzzle are not uncommon, coming up every year or so.

edited to add POP display and uncut panels