The way it works is this:
As has been said, there's a die roll regardless of whether a recipe is trivial.
Exceptional results are only possible when one rolls a 20 during the crafting attempt, at which point another d20 is rolled. In order to get an exceptional result (for those results that support them), the 2nd d20 must roll at or above whatever roll was required to successfully craft.
So if you need a 20 to craft something successfully, you need to roll another 20 to get an exceptional.
If you need a 11 or better to craft something successfully, you need to first roll a 20 on the crafting attempt and then something 11 or greater on the 2nd die roll to get an exceptional.
When attempting a trivial recipe, it doesn't matter what you roll to get a successful crafting attempt, but if you happen to roll a 20, then an exceptional is pretty much a given.