What type of flower did Persephone see when she went over to pick it?

Answer 1

It isn't told for certain;

"(Persephone and others) gathering flowers over a soft meadow, roses and crocuses and beautiful violets, irises also and hyacinths and the narcissus, which Gaia made to grow at the will of Zeus and to please Polydektor (the Host of Many), to be a snare for the bloom-like girl - a marvellous, radiant flower. It was a thing of awe whether for deathless gods or mortal men to see: from its root grew a hundred blooms and it smelled most sweetly, so that all wide heaven (ouranos) above and the whole earth (gaia) and the sea's (thalassa's) salt swell laughed for joy. And the girl was amazed and reached out with both hands to take the lovely toy: but the wide-pathed earth yawned there in the plain of Nysa, and the lord, Polydegmon (Host of Many), with his immortal horses sprang out upon her--the Son of Kronos, Polynomos (He who has many names)."

Answer 2

The flower favoured by the goddess Persephone was the narcissus as it was the favourite flower of Adonis, a mortal whom Persephone had a crush on.

Answer 3

Favorite plants of Demeter were mint, poppy, and barley.

Answer 4

one that Rhea made that Persephone never had seen before