When we had the "full-blooded" Silkies, before the predators got to 'em, the eggs we got were definitely small, but not near as small as what's in the picture I posted above. I'd say they were 2/3 the size of a golf ball, maybe a little smaller.
I'd have to save these for a while, since she lays maybe one per week. AND, I have to hunt for them, since she hasn't yet found the nesting box. My flock free-ranges in my 1/2-acre fenced backyard, so I do find the occasional egg out in the middle of the yard. haha!
I can't tell the size of the smallest egg in the middle because I don't know how large the others are. From this vantage point it looks like robin's egg sized? I would think they would get a bit larger than that, yes (but I'm a newbie).