Ash Grove is public domain, if we're talking about the same Ash Grove.

I wrote a cowboy song once and thought it pretty keen. Was in a craft store (of all places) and over the Muzak I heard the melody to my song! But since it was only one phrase and the rest was all different, I didn't worry about it much.

I hear a lot of things on the radio today that are similar to each other. Remember --- I think I said this before --- that I'm Thinking Tonight of My Blue Eyes and the Great Speckled Bird are the same song.