Jim,
Information is not copyright protected, no matter where it comes from. Copy/paste of other people's work is more than just information, though. You can, however, use facts contained in the text of someone else's work as long as you put it in your own words and include the link to the Find a Grave page as your source citation.
I'm not sure if the terms of use of Find a Grave prohibit it and/or if they permit individuals who contribute the memorials there to copyright their own work (WikiTree permits us to copyright our work here if we care to, although I've never seen it done by anyone here).
Even if it is not legally prohibited, if you quote someone else's work here, you are expected to acknowledge the source in order to give credit to the author.