Mary, If you've follow this forum for a while, you will have the opportunity tio read many discussions about definitions: weed, invasive, wildflower, native, introduced. Fascinating stuff to me, but these discussions often get compliated (and sometimes heated). While some think that a weed is just 'a flower out of place', the term 'weed' refers to plant that tend to colonize disturbed habitats -- which by definition includes all yards and gardens. It's not about appearance: a beautiful flowering plant can be a terrible weed. If you think of it this way, it doesn't matter whether your plant is the native or non-native dayflower, it is weedy if it behaves like a weed. The non-native dayflower is definitely weedy (but not a major problem, to my knowledge). I don't know about the native species, but many there are many well-behaved native species that are closely related to non-native weeds. A good example is the native honeyuckles vs the Asian honeysuckles.

Not sure. Maybe some kind of wild lettuce?

Agreed. If you miss some & it makes seed pods, it sounds like shooting a BB gun when mowed. If you pull it out of beds before this years' seeds fall, you should see little to none next year (as long as those BB's don't get flung back into beds from mowed area.) Break the seed cycle. The pods seem to show up within a day or two of the blooms, and ripen quickly, the sooner the better if unwanted.

Top is Chelidonium majus - Greater Celandine Below is a Symphytum species - Comfrey.