Emptying trash at night, but full in the morning?

Last night I emptied my trash and opend up 15 GB on my hard drive. Years of downloads andwho knows what else. This AM I start up my computer and see some wads of paper in my wire basket and of course wonder how they got there. I open my trash and see a folder for recovered files. I click on that and se a list of contents. Most of them read as plugtmp-1 (and other numbers up to 49. If I drag one of these out so I can open it, they do not actually open and if I "get information" on the file I find that their size is 0kb.

So my question is first, just an overview as to what is going on

and then, what should I do with these? There must be some reason for them being recovered. At least they don't take up room!

Thanks

Ron