Mazmur 78:23-24

78:23 He gave a command to the clouds above,

and opened the doors in the sky.

78:24 He rained down manna for them to eat;

he gave them the grain of heaven. ¹ 

[78:24]  ¹ sn Manna was apparently shaped like a seed (Exod 16:31), perhaps explaining why it is here compared to grain.