What is inside the snitch in the deathly hollows?

Answer 1

The snitch read ''I open at the close" when Harry put it up to his mouth. Well, the snitch opened at the end of his adventure... "the close" of his adventure... inside of the snitch held one of the horcruxes... one that Albus Dumbledore found and destroyed. The ring. It also was a Deathly Hallow. This was the Resurrection Stone: a stone that allows you to see your dead loved ones. This was the kind of comfort Harry needed before he faced Voldemort.

To answer your question in a much simpler manner: It was the resurrection stone, one of the 3 deathly Hallows.

I am guessing you know what that is if you have read the book.