Any time you plan to record something that has been written by someone else, never assume it is in the public domain simply because it's old.

Always do your research. As has been pointed out, some songs that we think are PD have several versions and the one we know is a more recent version that is still protected by copyright.

It only takes a few minutes to do the research and avoid the grief of a "cease and desist" letter or a claim against you for copyright infringement.

The only time it is "OK" to do covers of copyrighted material is:
1. For your own personal listening and recording pleasure where no one else will hear it.....ever.
2. If your publisher asks for a cover version of a song for a specific project and obtains the rights for that song pursuant to your written contract with that publisher.
3. You obtain the proper permissions for the intended use.

You can find my music at:
www.herbhartley.com
Add nothing that adds nothing to the music.
You can make excuses or you can make progress but not both.

The magic you are looking for is in the work you are avoiding.