Paleontologist's Pick-Axe // Dinosaur Headdress

You may exile tokens you control as part of the materials required. However, because they aren't cards and won't stay in exile, any abilities that refer to what you "used to craft" the back faces won't refer to anything.

Each time Dinosaur Headdress becomes attached to a creature, you choose one of the exiled creature cards used to craft it. You may choose the same card you chose the last time you had to choose.

If the materials required include multiple objects, you may exile some of them from among permanents you control and the rest from among cards in your graveyard. You don't have to choose all permanents or all cards from your graveyard.