Probably should have said "wind egg". They are small eggs often without yolks that are laid at end or beginning of a cycle. Here is a good picture on post 17 of this thread.
With a silkie in the pen, I could see how one of these would be mistaken for an egg from a silkie, but since there haven't been any more...and the crowing...
Your silkie doesn't have much of a comb for a male, but, I'm thinking he is male all the same.