These seed heads are so soft I couldn't even feel them when I touched them. The stems don't look very soft, though. Are they Cirsium arvense? I can't find anything that looks exactly like these photos. The second photo shows them in the foreground, which leads me to think that Creeping thistle might be the right ID. I see that the common name "Canada thistle" is a misnomer, as C. arvense is not native to Canada. [Edited]As an aside, this area has been planted to look natural. I think these might have been deliberately planted.
The flowerheads certainly look like Creeping Thistle; less sure about the plants, they don't look typical, being shorter, stiffer, and more densely leaved. But that could be an environmental effect of the growing conditions on gravelly ground with (perhaps?) salt spray from the water (is that the sea, or a lake?).
