The most I've ever seen at once in the yard is six. This year, I've seen four at the same time, but given how they were flying around, I suspect more.

They are fun to watch and listen to. They like to scream at me when I go outside. It's interesting to watch them cracking open the big sunflower seeds. They have a good hammering action. So do the brown thrashers.

I have heard that jays are smart enough to figure out simple "puzzle" feeders, but I don't have a puzzle feeder.