Just went through and collected all the Dragon Priest Mask and honestly feel pretty good about it. (For whatever reason when I placed the wooden mask it glitched out and didn't place) :
Every Dragon Priest Mask In Skyrim, Ranked
Steam Community :: Guide :: How to obtain all Dragon Priest's Masks (Special Edition)
Dragon Priest Masks – Black Owl Studio
ALL 9 Dragon Priest Masks Guide (No-DLC) - TESV: Skyrim Special Edition - YouTube