As has already been said, as far as the vehicle registration, the officer likely already knows who the vehicle is registered to and whether it's expired or not before he walks up to your car, or at the least, he can easily find that information out.
The proof of insurance is a different matter. The officer will need to see it to know if you have insurance or not. To him, it doesn't matter what the reason is that you don't provide it to him. Left it at home, misplaced it, lost it, destroyed it, or just refuse to provide it because you feel you have the right to refuse. He can't "force" you to provide it (unless he is able to search your car and happens to find it there). He can only issue you a ticket for not providing it.
But your attitude could play a part in what happens next. Being upfront and letting the officer know you have left your documents at home could help your situation.
In my experience... one time that this sort of thing happened to me, the officer agreed to hold my drivers license and allowed me to bring the documents to the police station and retrieve my license.
Another time, in a parking related matter, I was issued a ticket, but I was allowed to bring the required documents to the police station where they then "invalidated" (cancelled) the ticket.
Of course this won't always work, and is not at all likely to work if you are far from home.
Keep in mind, (as far as I know, in most states) the real infraction is that you "don't have insurance"... that you failed to provide proof when asked, is secondary. In many cases (likely nearly all cases), if you show up in court and provide documents that your insurance is current, and was current at the time the ticket was issued, the judge (or the prosecutor) will likely dismiss the case with no penalties. But, what the officer has written down on the ticket about your attitude and what you told him at the time, may have an effect on how this all plays out.