In a user's Profile page, in the Owned Cards tab you can see all of the cards that that user owns.
To open the Owned Cards tab for a user,
Open the user's Profile page by clicking his or her profile picture anywhere that it appears.
Click Owned Cards in the tab row under the row of hyperlinks.
You can click any card in this tab to see the Details view for that card. For more information about the Details view, see Card Details View Layout.
For more information about changing the owner of a card, see Changing a Card Owner.