No. I don’t think anybody has seen one. (There are a few unexplained, bright objects in the universe, but nobody is seriously labelling them as white holes.) That suggests to me that they don’t actually exist, because we should have seen some if they did exist. And that, in turn, says that our theory of gravity is not quite right, as the current theory says that white *can* exist; and, in astronomy, something that *can* exist pretty much always *does* exist somewhere.
No. White holes are a funny *quirk* of Einstein’s mathematics. They fall naturally out of his theory of general relativity and I highly doubt we will ever observe one. The reason we will never observe one is because we cannot travel backwards in time. White holes are essentially the time reversal of a black hole (they spit stuff out rather than suck things in) so we would need to either travel faster than light (which is impossible) or travel back in time (again, impossible) to observe one.