You need to assign it to a quickslot first, for console you can assign it to any of the D-Pad, then like you would select a potion you now select the Trophy and press D-Pad up to activate the trophies animation

Folks these same questions have been asked and answered quite a few times in recent posts. The forum does have a search function. OP, what you have, Ogre Toe Ring and Flawless Tail Feather, are more correctly called collectibles. These are consumable and vendorable items that drop from specific creatures. Trophies are quest rewards that cannot be sold, but can be slotted in quickslot or otherwise used to produce some minor benefit or mostly some graphic effect. Trophies stay in your inventory until you destroy them.

As for collectibles, they work differently on PC and Console. On PC, they get 'used' like a food or drink, which consumes the item and adds it to achievement journal. Each one can only be consumed once by the same character, and can be sold after that if another copy is found. For the console, I still have not seen any confirm response on how they work, but it seems there are 2 likely scenarios. First, it gets added to your achievements as soon as it is in your inventory. You can check this by opening your journal and check TROPHY on the achievement tab. There you will find a list of all possible collectibles. There are several groups of them, and each time a group is completed, a dye unlocks. If the collectibles in your inventory do not show up as completed in your journal, then try to 'destroy' the item and see if that adds it to your journal. Post which way works, so we can pass it along to your fellow console users.

On consoles, if you get a collectible in your inventory, it counts towards the achievement, you may then destroy it or sell it, or give it to your alt so he can benefit from the collection achievements as well.