To add to that, let's say that the content you had created your compilation from was public domain material - meaning that it had no rights holder and anyone is free to do with it as they want. Even still, if someone uses public domain content to create their own work (a "derivative work") that person owns the copyright only to their creative additions, not to the original public domain content. The fact that someone creates a derivative work using public domain material does not change the copyright status of the original material, and others would be free to use it as they wish.
Note: A common misconception about "public domain" is that it refers to things which are in the open and available to anyone. That is completely false. Believing that and acting upon it is a good way to get sued. For a good overview of public domain - what it is, how works become public domain, etc. - check out [SEE NOTE] and read it carefully. The same author has another page at Stanford titled "Public Domain Trouble Spots." A link to that is here [SEE NOTE] and I suggest reading it as well. It's all just the beginning, but that's the place to start.
Note: I can't link to any URLs... fun. Anyway, to find the pages I recommend Google "Stanford public domain." The first two search results should be it.
