There are many things on Earth they find quite desirable, and I have a good number of whistleblowers who have given me information to that effect. My whistleblowers are predominantly ex-military, some of whom are still working for the secret government and who have spoken to me off the record. The aliens are very interested in our gold, for example. Our gold? Our gold? Yes, I'm told that gold on Earth is relatively easy to access when compared to getting it off an asteroid, which obviously would have issues when it comes to mining for gold.