GUI trash different from terminal trash
Each volume has its own trash, identified by user, in addition to the trash in your home directory. Trash shown in the dock is the aggregation of all of them.

So, in your $HOME you'll fine a .Trash, as will each user. But, also if you have other drives mounted, in the base of each will also be a .Trashes, within which will be directories for each user, identified by UID.