I have one gold star that has laid a few double yolkers, no triples, and have not ever heard of one. The bird is not all that big, but lays hefty eggs reliably.
The egg layed with the most yolks had a whopping nine. I have had a couple of doubles, even one very tiny double, but no triples here. I definitely do not want any of my hens to lay one big enough to have nine, yikes!
Here's a pic of one in a post: https://www.backyardchickens.com/forum/viewtopic.php?id=392493 There is a user on here - wildorchid053 - who has a picture of their triple yolk egg as their avatar.
