Lester -

A few of the music shops in our current area (Kansas) seem usually to have the triangular picks in stock fequently enough to satisfy the demand, although it's sort of "hit or miss" whether you'll find them on any given trip in.

I think Lin got her first few from Dusty Strings (Seattle Area), and at least some of the instrument vendors at the Winfield festival usually have a few, so I'm sure they're not just a local thing.

I can't recall seeing any of them that were "branded" to suggest who makes them.

Unfortunately, nobody seems to know what to call them, so I can't even suggest a "name" for the type that would be consistently recognized.

About the only other thing I can add is that I can't remember seeing them in anything but the standard "brown imitation tortoise" plastic common for guitar picks, (but that may be just because that's the color that Lin In Kansas prefers).

John