Another plant in question...

No 2 looks like Kale. The other could be some sort of Brassica perhaps but there's no scale in the picture so I may be misjudging the leaf size completely. Could even be Groundsel if the leaves are small.

They are both maybe 3-4 inches tall, so rather young still...

just some pix hints ...

first pic.. taken at a good angle.. but taken into the sun .. for some reason.. it reminds me of melon ...

second pic.. straight down ... it really makes ID hard ... we dont quite understand why.. but it does ... yes.. it reminds me of something in the greater kale family ....

throwing in a scale or something usually helps ... which when taken down.. usually ends up the toe of your shoe ... lol ...

i offer said advice on pix.. because i have a feeling you will be back often ... with your seed dumping theory ... lol ...

ken

They might also be wildflowers, or weeds, depending on your P.O.V...

Thanks for the pic-tips and other suggestions...I guess I'll see what they turn into. I'm pretty sure they aren't weeds largely because there is nothing similar growing anywhere else and there are definitely kale plants in the bunch. I wasn't expecting seeds to be germinating in late December! Fun surprise.