I would like to serve food to a friend who observes the restrictions against eating Chadash grain products, but I don't have access to a guide on identifying Yashan. However, I have heard, that certain grain products are known to always be made from winter wheat. Can you give me some simple rules of thumb to help me find flour and other grain products in the local supermarket that are certain to be Yashan? Please include guidelines for all times of the year.
You can get a pdf of R' Yosef Herman's authoritative "Guide to Chodosh" by sending a blank email to firstname.lastname@example.org. In the period immediately following Pesach, all food is Yashan. Starting around August time things start to get more complicated and the "Guide" can help you navigate. The first issue (containing some introductory information) comes out in the fall with updates issued every few months.
There really isn't any easy rule of thumb, as one must take into account packing dates, place of manufacture, etc. for each ingredient. Keep in mind that anything from Eretz Yisrael with a reliable hechsher will be yoshon. It happens to be that gefilte fish is also always yoshon, for some reason. Anything else - check the Guide!