Ok, I did some research. I started back at the beginning and found 2 eggs from level 1 through the level I'm at now, 409. There are big eggs and little eggs everywhere, so it's confusing. But if you check out the video I attached these are medium sized eggs with bows on them. I had to scroll WAY WAY up to find some of them (levels I won't be to for years). :) Hope this helps!
https://www.youtube.com/watch?v=dKoeJroXRnY

I don't get it either. I'm guessing maybe you have to beat the level near where the egg is hidden, but the eggs were located like 25 levels away from where I'm at. Confusing.