Lots of great suggestions...One more is Glenda's Creole Kitchen just down the road from Pochet's near Breaux Bridge. She makes great authentic Creole food!

Jack Bond

A couple of good places for boudin on your way to Mamou.
Best Stop in Scott
Raymond's Grocery in Eunice (formerly Johnson's Grocery)

Link 1 is a bit outdated in that it says Johnson's is closed. It's been reopened for a while now at Raymond's on East Maple Street. Coming north to Eunice on HWY 13 you take a right at the first stop sign as you approach Eunice, then it's a short way on Maple on the left.

Link 2 is for Chris' Po-boys in Lafayette. The pork roast poboy is really good. See Link 3, post 27 for my report from last June.

Dwight's on Johnston Street in Lafayette north of the Acadiana Mall is popular for boiled crawfish daily and for barbecue on Sunday.

That's in addition to the already excellent suggestions everyone else already made.