If, by "trash", you mean into the computer's Recycle Bin, then, as ~The One~ says, absolutely nothing. They stay in the Recycle Bin forever until you manually delete it, empty the contents, or right-click and click on "Restore" (to put it back where it originally was on your computer).
Your computer might be set to empty the Recycle Bin automatically once a day or something, but apart from that it's safe. I did know a fool who used to do this for compression, but WinZip or WinRar are better for that.