Star of Bethlehem (Ornithogalum umbellatum) is a good example of why wildflowers and weeds are the same thing. It grows in grassland (mainly in East Anglia in this country) but is reported to be toxic to grazing animals.
  That's not really an issue here in New Cross Gate so I've planted a scattering of bulbs in the lawn and they look nice- the starry flowers unfurl and open up when the sun shines on them. I don't cut the grass till mid-summer which gives them the opportunity to bloom.