Egg in the garden this morning

Good morning, I have found a perfect little white egg in the garden this morning (fully intact) it was in the middle of the lawn covered with yesterday’s grass cuttings. We have two resident wood pigeons who have been nesting and the magpies have been making a nuisance of themselves so I can only assume it is from their nest. My question is what do we do with it? I am loathed try and put it back in the nest in case I am wrong, can we hatch it ourselves? Please advise, so far we have moved it into warm grass cuttings but not sure what on earth to do next?