A weed is an unloved wildflower. Both are plants.
We have been tricked by giant chemical ag companies into thinking we want putting greens for our gardens, instead of the meadows that really bring life and beauty. But at least there is now a cultural rebellion brewing against everything the Monsantos of the world stand for.
I think of weeds as being whatever plant you don't want in your garden. I've collect seeds a few times from plants that would typically be considered weeds. Some of them sprout and some don't. I'd love to grow some Texas Dandilions that will grow wild here but no success yet. Often, when I find a bunch of wild plants, they get mowed down before they go to seed. I've seen them growing in lawns as well as wild in fields. Why they won't grown in my garden soil is a mystery.
Btw, I think the dandilions complement the primroses nicely. Very pretty.
A "weed " is a non native species which overtakes an area & provides little in the manner of wildlife support. Plant nazis' that invade, replace, destroy, & become a monoculture. Daiseies are aggressive but manageable. Garlic mustard, purple loosestrife, Euro buckthorn, Asia honeysuckle, & "Canadian" (eur-asian) thistle are difficult to control here in the midwest of the USA. Other areas are battling other invasives. The UK is battling the North American gray squirrel tho it isn't a plant. Some we just have to accept....to an extent. Dandelions are nutritious & non competitive.
It's all in your mind, I keep a bee friendly yard so dandelions have moved from weed to desirable volunteers. Like my cilantro, arugula, mint, oregano, daffodils, and potatoes which come back on their own every year. I once had some very persistent kale which I suppose was a weed because I only exterminated after a long siege.
Sometime back , got a note from the local HOA , complaining about the weed in my lawn . I wrote back , where I was from, clover was a financial crop , farmers planted to both improve the soil and also used as feed . The crab grass that makes up most of the local lawns was the only other thing growing locally that's only purpose was to keep the soil from washing away when it rains , but was considered a weed we tried to eradicate , where I was from . They wrote back the clover was the weed , and had a lparticularly verilent strain they wanted removed . So crab grass weeds in the front lawn , and lovely flowering clover ground cover , in the back yard . Got cha !