South of Bonta, in Cania Fields. There are 2 huge patches on two maps. Go south until you find Wheat, Barley will be on it's left, Rye is left from Barley.
Yeah what the heck. Why are there such few spots.... there are tons of peeps out here farming this lol. Whose idea was it to put half of rye patches in two spots in the whole game >_