Yoshon refers, very roughly, to grain products that have grown through at least one Pesach. Some have the stringency to eat only yoshon grains.
How does one go about identifying yoshon flour and other products to use in one's kitchen? I have seen different types of advice here and here, from looking at the date or date code on the food, to buying only specific brands or products. In addition, some packaged foods have a heshcher which indicates yoshon status, but this is not particularly common in the U.S. (especially with staples like flour).
In general, what is the easiest and/or most reliable way to identify grain products as yoshon?