Let me enlighten you. Congress had the flags returned in 1900, when they passed a law. You won't be getting those flags back.
State organized military units didn't give the flags back. They kept them ~ after all the losers had argued it was all about "states' rights" hadn't they.
The Indiana state capitol building rotunda literally bulged with the mass of Confederate flags taken captive. You oughta' seen it!
The Indiana organized units were, after all, the very core of Grant's advance and had ample opportunity to retrieve the colors.