I found a fingernail in my frozen food product. I contacted them and they want me to send the object back, what should I do?

I called the 1800 number on the box and let them know what happened. I found the fingernail in my mouth after eating a spoonful of the product. The woman I spoke to, apologized and offered me coupons. She also said she will mail me a ziplock bag in 7-10 days so that I can send the fingernail to them. Other than being disgusted, I was not hurt. Should I send the fingernail to them? What advice can you give me on what to do?