The site has been cleared since these photos and replaced with a department store. The last 2 pics show the site as it was - the last having just Erigeron sumatrensis 'in shot'. However, looking at that last photo - enlarged - again I wonder whether the plants with whiter heads might have been Erigeron (Conyza) bonariensis too.
Thought to be of Sonchus genus? But could be of Carduus from the prickles size?