I've had hat tricks with Flintoff, Jermaine Lawson and James Harris. As for the latter i'm not sure if he's a regen but i'm in 2012 and signed him at the start of the 2011 season (evidently his club didnt think it was worth renewing his contract despite him having taken 297 first class wickets at the age of 20!!! Since i have signed him he's taken a further 147 wickets (during his first full season and the start of the current one) taking him to a career total of 440 FC wickets at an average of 21.50. He's also taken 130 one day wickets at 21.23.
Anyway here's his hat trick, unfortunately never took shots of the other two hat tricks.
EDIT> Sorry forgot to upload.