Originally Posted by Steve Kroll
Tripe is actually a fairly common ingredient in Pho - or at least in Vietnam it is. Probably less common here.
Most of the Pho places I've been to in Washington state offered tripe (as well as tendon and occasionally other more exotic options). I haven't seen it at any outside of Washington state, probably because there's a decent-size Vietnamese population in Washington.
Random Mistakes: The fatty bits you found in your bowl may have been fatty flank. It's another common one out there. I can't be sure, but it also looks like there may be bits of tendon in there, too. That was a common combo at a lot of the places back in WA; fatty flank, tendon and tripe. I've tried it but I personally prefer my rare beef or meatball. :)