I've just got back from 10 days in Italy visiting Bologna, Florence and a trip to the hills near Bibbiena too.
While in Florence I visited the Uffizi Gallery - an amazing evening looking at some incredible works of art. While in the gallery I spotted a couple of dandelions in Filipino Lippi's paintings: the one here is 'The Penitent St. Jerome' and is tempera on wood, dated c1493 - 5.
I have very elegantly marked where the dandelion is on the painting. It's a dandelion in seed, quite delicate and fragile with the dark of the rock behind giving it contrast.