The great thing about having a fluid canon on this site is the fact that we can pick and choose what we like, not just from our own perspective, but from everyone else's. Every single one of us has a Foundation in their heads, and no two are alike, but they are constantly changing, and redefining themselves based on the others. Characters and concepts evolve by popular demand.
This thread is for helping that process along. There may be aspects to your Foundation that you only ever touch upon in your tales and skips, or perhaps you can't even find a way to include them at all. So tell us something about your headcanon that nobody knows much about. It could be anything, from a scarcely mentioned Foundation department, to a different perspective on a GOI, to a character that's always in the background turning out to be monumentally important. You never know, someone might like the idea.