Also Isolation, Hancocks, Carrigain and perhaps most famously Field (and Tom and Willey). They will take food from you and go an stash it in the bark of a tree for later consumption. This is why they fly away and then return. Most of the time you will get a mating pair, and they occasionally allow one of their brood from this season to hang around for some of the year before booting it out to be on its own.
Note that I've seen a hiker break off a small piece of sandwich and hold it up for a jay. The jay went after the big sandwich in the other hand...
p.s. If you put food on your head or hat, they will land there too