Fried egg

I always thought bamboo is the fastest growing plant. But I think I found something growing even faster.
On the path between hour house and the office on the railway sleepers I saw this little bright yellow spec about 1cm in diameter. I did examine it closer but this morning on my way to check the mail I saw that this little spec had grown to about 4 centimeters. But it had not only grown in width it had also grown significantly in height. It was about 1cm high and had grown the "egg white". The colour was very intense for about 3 hours and then it started to deteriorate until it was almost brown.
I will try to find out what the name of this fungus is.