Separate names with a comma.
Interesting! I saw similar terminal flower effect in a Penstemon:
Definitely, not Nolina, but Yucca instead. There are last-year dry fruits visible in the second photo just above the rail. For Denver area, Yucca...
No, Lactuca seriola, I guess. Notice the bristles along the leaf midvein. Sonchus does not have those.
You can smell it in a grocery store :)
Even tasting some Apiaceae plants may have bad consequences. Both celery and parsnip have very characteristic smells. I'd do only this instead.
The leaf venation is not of the orchid type.
Another ancient online book on Flora Italiana: 1 - Flora italiana; - Biodiversity Heritage Library
There is also a good crowd-sourcing group on Facebook, with 92+ thousand members, many from Europe, some from Italy:
You can still find online some old editions of Flora D'Italia:
Biblioteca Digital del Real Jardín Botánico
Biblioteca Digital del Real Jardín...
Raphanus sativus would be another possibility.
Looks consistent with V. palustris. Check however, if it is listed for your place. There are few other look-alike species.
Chorispora tenella or related.
Looks alike, indeed.
Probably, Lycopodium, similar to L. phlegmaria.
No direct harm, unless it is too dense and takes too much water and food resources. Unlike the dandelion, it is less invasive and easier controlled.
Not Taraxacum, which does not have stem and branching inflorescence. This is Sonchus sp, most likely.
Cyclamen for the start.
The list of plants you seeded might help.
OK, this would fit better - Coleogyne ramosissima (2014.05.02_08.15.48_IMG_7781).