"Salad days" is an idiomatic expression, referring to a youthful time, accompanied by the inexperience, enthusiasm, idealism, innocence, or indiscretion that one associates with a young person. More modern use, especially in the United States, refers to a person's heyday when somebody was at the peak of his/her abilities—not necessarily in that person's youth.
Famous quotes related to salad days:
“My salad days,
When I was green in judgment, cold in blood,
To say as I said then!”
—William Shakespeare (1564–1616)