D&D Playtester for WoTC since 2012
A wiki on the book says Ed Greenwood Presents Elminster's Forgotten Realms - Wikipedia
back in January 2012 at the Dungeons & Dragons new products seminar, lead developer Mike Mearls gave fans of a preview of the D&D supplement 'Elminster's Forgotten Realms.' Mearls told the crowd that Wizards of the Coast staff approached Greenwood to ask 'why don't you take all your campaign notes, all the information you've been putting together for your campaign and lets compile it into a book? Show us the realms as you've developed it in your campaign setting and lets get that to everybody.' It's not often that fans get such an inside look at the creation of one of their favorite settings, but 'Elminster's Forgotten Realms' completely pulls back the curtain on Greenwood's design.