Well - it doesn't say much for the quality of the compost, does it? Pic 2 is a nettle, for sure. I think you must have the record for nurturing one of those! Pic 1 could be another weed, but the reddish tinge to the leaves could (just could) be Amaranthus (Love Lies Bleeding). As an experiment, you could keep it in a pot - probably potting it on rather than keeping it in a 3" pot - and see what happens. I certainly wouldn't plant it out - who knows what you might be introducing to the garden.
As for pic 3 - it looks the most promising, and probably is a chincherinchee, though I've never grown them, so would bow to anyone else's experience. But it looks like the first leaves from a bulb, so I would be quite hopeful.