Pete,
the aged effect on the Oak vase works, I honestly thought you'd hollowed an old round fence post at first.
The tall yew vase I like, the small foot to lift it away from the base could be smaller to hide it better, make it more of a floating effect. Not sure about the lid/finial, it's a bit strong with the sharp angles and heavy looking top part.
The last yew pot is a bit formless, the long straight sides make it look like a pencil pot, I know you said it's rescued from the firewood pile, so had no option of what you got, but this shape would work with a strongly coloured piece of yew, where the grain effect is the main feature.