When I was a kid I was told that umbrellas grew in the rain. When it rained they bloomed into big, fully grown umbrellas and the closed up ones had to get wet before they got bigger.
A childhood belief about plants

others believed things like this
- That when it rained it rain all over the world— Ann
- I used to believe reindeer made it rain because for many years it rained on christmas eve night.Anon
- I used to believe that mushrooms in the grass grew if it was sunny and rained at the same time.— Ryan
- that as I grew up, my parents would "grown down," then I would be the Mom and Mom would be my child.Anon
- When I was around four,I used to think when it rained in my area,it rained over the WHOLE world too...Anon
- When I was a kid I thought that when it rained, it rained all over the world.
Anon