The Trash bin is the unison of multiple directories (folders) that are placeholders for files ready to be unlinked. You have a .Trash directory in your home folder. Every mounted filesystem has a .Trashes directory that holds files moved to the Trash bin. Within this directory the operating system creates a directory with your user id (which is a number) as the name of the directory. The file(s) that you wish to trash are placed within this directory. While it would be typical to find the 501 directory this is not always the case.
Background: Every filesystem mounted in OS X has or is given a volume name. We list the mounts in the /Volumes directory in long format to determine the volume name.
ls -l /Volumes
Once we have determinded the volume name, we list any folders in the .Trashes directory. We must take special care to escape "\" any volume names that have spaces in their name.
ls /Volumes/DPS\ 2/.Trashes
The folders names should be numbers, such as 501 502 503 …… Now open a Finder window to show you the content of the folder.