Epimediums, sometimes called bishop's hat or barrenwort, are perennials

they are lovely plants that do well in shade inparticular. The flower shape is similar in shape to a bishops hat or 'mitre', hence he name. there are deciduos and evergreen plants in the genus too.

and I thought it was a way of folding a napkin lol

That's the problem with common names :-)

I also know of a cactus (Astrophytum) called a bishops hat and also a type of hot chilli fruit

Cliffo 'I' thought it was what a bishop wore on his head... This really is where 'common names' let you down.