If it's really over 20 years old, don't worry about composted it first. Go for it, and use it as a soil amendment, or make a tea brew out of it, and use it as a foliar/soil drench on various plants or your lawn.

Is it the berry that you have or is it already ground? If it's the berry, I would check to see if it will germinate before putting it out on the lawn. Hard to say how long some seeds will last.

Mary Ann