I understand that for supporting documents required for uk standard visa that we must send in my wife's Filipino passport.
The question we have, is do we have to also send in actual US Green card?
I shouldn't think so. They need the actual passport because they need to stick the visa inside.
The guide to supporting documents says
All documents must be originals and not photocopies.
However, the online application asks you to upload the supporting documents, implying a scanned copy of the document. It also says that if you cannot upload the supporting documents you should bring them to your biometrics appointment so they can be scanned.
Furthermore, US law requires green card holders to have their green cards in their personal possession at all times, so it would not be reasonable to require the green card to be held by the UK while the application is being processed.