The easiest identification is a seedling like this where you can see the distinctive seed, in this case globe thistle.
nasturtium: another seedling straight from a distinctive seed and nasturtiums have distinctive leaves as well
This is a knautia melton pastels which I bought earlier this year in bloom, it has a new flush of flowers late in the year. I love those pincushion flowers which the bees love so I bought a pack of seeds which are doing well as young plants so hope to have lots of flowers next spring/summer. I want some scabious as well (they're all the same sort of plant to me even if they are different scientifically) so will be sowing those seeds in the spring.
I'm having more success with the echium and monarda seedlings, maybe the ones I planted earlier, in the summer, were overwhelmed by the self-seeded oeonothera.
Narcissus Green Eyes. I could not resist this pack of bulbs yesterday, the colour is intriguing - blue shading - but possibly just in the pic, in the spring I'll see what they really look like.