Now this is a bit of Irish tradition I did not know. During the annual St. Patrick's Day parade in New Orleans cabbages are thrown from floats and parade walkers. So the question finally came up as to why cabbages are thrown in St. Patrick's Day parades. Eat corned beef and cabbage yes, but having them thrown? News.
Actually New Orleans may be one of the only places this happens, the tossing of cabbages, I've never heard of this before but here is the reason cabbage is normally part of a St. Patrick's Day meal.
"In 1845, when there was the potato famine in Ireland they ran out of potatoes, so they started using cabbages because that was the next big staple food. In Ireland though they used bacon for their meals with the cabbage. When the Irish immigrants came to America, they couldn't afford the bacon, so they used corned beef, and that's how we got the corned beef and cabbage tradition."
You learn something new every day.
New Orleans parade organizers advise: "We always ask our members to toss the cabbages not throw them overhand. Sometimes after a few drinks they can throw overhand, and that's when people can get hurt."