A leaf is the answer
I come once a year, a day of cheer, A time to laugh and not to fear.
My jokes are many, and some are bad, But they're all in fun, so don't be sad.
I'm not a holiday, nor a festivity, Yet I'm celebrated with much levity.
What am I?
I am born in fear, raised in the truth, and I come to my own indeed. When comes a time that I am called forth, I come to serve the cause of need. What am I?