Frosty Morning Cliché

I don't actually know what tree these 'fruits' or seed pods are on. They have a lovely architecture and are extremely tough. They're a vibrant green in the summer and then desiccated in the winter - remaining hard and crunchy underfoot for a long while after they've fallen.
Today the world outside looked crisp and fresh but it felt too cold to stay in the garden for long, unless you were working to keep warm!