How can I display contents of trash using terminal?
You can run

ls -al ~/.Trash


to show the content of the Trash of the current user.

To see the content of all Trashes, use

sudo ls -al /Users/*/.Trash


from an admin account.

And if you also want to include the content of the Trash on external volumes, use

sudo sh -c 'ls -al /Volumes/*/.Trashes/*/'