I think these are Black Knapweed, but I’m happy to be corrected on this. (And I have been…. this more likely to be a Creeping Thistle!)
I should be investigating possibilities of a few tablet based field guides that I can take round with me – it’s far easier to identify things at the time rather than later. Having said that, I used to take my birding field guide on my trips out but I was seldom referring to it – not that I knew all the birds, but I was seeing the same things all the time – it just became dead weight.
(The crop is wheat. I couldn’t choose between the two compositions – though having prepared the post, I think the break in the tree line of the second, at the left frame edge is a bit distracting. )