Not so much a belief, but an assumption. We used to drive the same route to go camping and along one road was a farm with a signpost out front. The top one said RABBITS FOR SALE and the one below it said FRESH EGGS. I always assumed the eggs were rabbit eggs. I was about 14 before it dawned on me that the eggs were chicken eggs.
A childhood belief about general

others believed things like this
- I used to believe that bunny rabbits hatched from eggs, since the Easter Bunny gave you eggs.— goat
- I used to believe that only brown eggs came from chickens. I thought white eggs were made at the store— Destiny
- When I was a kid, I used to believe that cadbury cream eggs real uncooked eggs in the middle Anon
- In my youth,I was always convinced that my chocolate easter eggs came from my uncles chicken farm!— Jamsie
- Rabbits lay eggs— Maria Eduarda
- When I was little I believed rabbits laid eggs. Anon