salad days \salad days\, noun:
A time of youthful inexperience, innocence, or indiscretion.
Salad days was coined by Shakespeare in Antony and Cleopatra: "My salad days,/ When I was green in judgment, cold in blood."
Those were his salad days, and he thought they might last forever.
-- David Gergen, "They Love You. Watch Out",