i wouldn't remove, I'd be watching most carefully. Very interesting
they are delphs
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Possibly Geranium nodosum
No harm but pointless as it's just the fruiting body of an underground network of mycelium. They're very short lived and you may not see those again for another year.
Kitchen fork for small pots, garden hand fork for the big pots. If totally packed with roots, sometimes I just whack them with the side of a trowel
They're annuals. I think they arrived here in a bag of compost. Some years ago they suddenly appeared in lots of my pots of seedlings, Never been here previously.
Looks like a willow species to me, not a buddleia anyway
Datura stramonium, aka Thorn Apple