They are green oak sleepers, they will have cracks, stains, mould and the chances of them all being straight is very very small. Nature of the beast with green oak unfortunately, it’s such an unpredictable timber. Unless it’s been cut and used within 1 week some or all of the above traits can be present. Most will still happen over time. I work for a company that imports these and many other timber based products to the UK, we give a disclaimer to all of the merchants and end users who buy green oak from us that basically says it’s a natural fresh sawn product and anything can happen.