the goose that laid the golden egg – someone who brings prosperity to sb.

a hard egg to crack – a difficult person or situation

You cannot make an omlette without breaking eggs.- Sometimes you have to do unpleasant things in order to achieve your desired goal.

Don’t try to teach Grandma to suck eggs. – Don’t teach a wiser and more experienced person.

walk on eggshells – act with great care in order not to upset sb.

he that would have eggs must endure the cackling of hens – you need to endure irritation to get what you want

put all eggs in one basket – make everything dependent on one thing

one egg short of a dozen – a stupid person, a halfwit

a chicken and egg problem – problem of cause and consequence

Don’t count your chickens before they are hatched. – Don’t think you’ve got sg. until you get your hands on it.