#1 Dianthus sp.??

#2 Do you recall planting Antennaria or perhaps even a Lychnis/Silene sp.?

My immediate thought was Dianthus but I'm havering due to the fact the foliage doesn't look quite opposite. What is the leaf texture? Does it tally with Dianthus?

The tree leaves on number two look as if they're going to be quite deeply toothed. Possibly even spiky like a thistle or Echinops.

wondering about rose campion.. lychnis ... scroll down to the high lights pic .. its a WAG.. ken

https://duckduckgo.com/?q=lychnis+rose+campion+seedlings&t=ffcm&iar=images&iax=images&ia=images&iai=http%3A%2F%2Fpics.davesgarden.com%2Fpics%2F2006%2F06%2F03%2Fgregr18%2Fc12f3d.jpg

I did sow both dianthus and rose campion (lychnis) so I suspect you nailed it! Thanks!

Not rose campion. The emerging true leaves are unmistakably toothed and the seed leaves are the wrong shape and insufficiently felted.

eta I've just been out and examined some Lychnis seedlings and I'm not quite so certain now. What I see as teeth could be clumped fibres. Still not convinced but less sure.