Have we said everything we have to say on this topic?

Maybe not. I asked a francophone friend at work yesterday about pissenlit, and he told me about a saying: Bouffer (ou manger) les pissenlits par la racine. ("To eat dandelions by the root.") It means to be dead and buried. I told him that we say "pushing up daisies."

There is an online Anglo-Norman Dictionary at the Anglo-Norman Hub site (link). Searching on the English dandelion, I find two entries:
Quote:
dandelion (?)
squinant, dellion, mastic Pop Med 330.24

dandelion
Dens leonis: g[allice] dent de leon Bot Gloss 119
den[s] leonis [...] G[allice], dent de lion, A[nglice], doleroune Alph 49.7
dente de lyoun Medical Codeswitching 145
Alph is Alphita, a medico-botanical glossary, ed. J. L. G. Mowat, Anecdota Oxoniensia, Med. & Mod. Ser. I, ii, Oxford, 1887, and shorter versions in BM MSS Addit. 15236, ff. 2r-22r, 172v-197v (A), and Sloane 284, ff. 1r-48v (B). (This work is from about 1400, almost the end of the Middle English period. Digitized on Google Books link.)

Bot Gloss is T. Hunt, ‘The Botanical Glossaries in MS London BL Add. 15236’, Pluteus 405 (1986-87), 101-150.

Pop Med is Tony Hunt, Popular Medicine in Thirteenth-Century England, Cambridge, 1990.

Searching on the Middle English word deleroune 'dandelion' (see above), I came across this discussion (in German, link) about the words dandelion and pissenlit. One of the commentators there seems to think that dandelion was never French, but only Anglo-Norman. Though, the discussion is in German, one person has copied the entry for dent-de-lioun from the Dictionary of Middle English, which includes citations not in the OED1 entry. Another entry in this dictionary, under wort, has another Middle English word for dandelion: bitter-wort.

Ceci n'est pas un seing.