Atharva Veda, Book 8, Hymn 7, Verse 20:

(Ralph T.H. Griffith translation)

"Asvattha, Darbha, King of Plants is Soma, deathless sacrifice Barley and Rice are healing balms, the sons of Heaven who never die."

Asvattha ( Ficus religiosa), Darbha/Kusha (Desmostachya bipinnata), Soma (a number of plants are identified as Soma plant, one among them is fly-agaric mushroom, 'Amanita muscaria'), Barley ( Barley is a cereal grain derived from the annual grass 'Hordeum vulgare') and Rice ( Rice is the seed of the monocot plant 'Oryza sativa')