This is an old thread but I feel the need to voice a warning. Don’t let your birds eat a large quantity of dry (unreconstituted) instant mashed potatoes. When they drink water, the potatoes will expand in their crop or stomach and make them very sick or conceivably kill them. Many years ago, I had a boyfriend who did this (go figure) and became very ill.
Did Ann Landers tell you that? Abby's twin sister also advised against feeding song birds rice for the same reason. Let the birds be birds, and like one poster here has already said, take everything most people tell you with a grain of salt.
The real truth is that a birds crop or 1st stomach is designed to hydrate or make dry grains swell up in preparation to being ground up in the gizzard.