Put it in a baggie and keep it in the refrigerator until you can have a vet look at it. Is there any possibility she could have tried to eat a mouse, lizard or even a toad and hacked up a piece of it? If she shows any sign of coughing up blood, or acts in any way "off", get to an emergency vet and bring the tissue with you. It may not hurt to give an ER vet a call anyway and get some advice as to what to watch out for tonight, or whether to come in straight away.
Thanks. Im actually not at my house right now. And I already put it in a baggie and in the fridge. My dad said that she might have eaten on her walk. Thanks for you help.
And I will probably call a vet tonight.