Karen, please take a look at the clickable links at the top of this page for the many discussions we have had about the various versions of this song. Pay particular attention to the one that has (origins) in front of it. That one proposes some possible dates of first publication.

Your other question about easy to learn songs for St. Patrick's Day might be found here and in the links shown in Mary in Kentucky's first post. If you can't find the answers you seek there, I suggest you post a brand new thread with a title such as "Quick & Easy Songs for St. Pat's".