rice plant
稻 centers on the rice plant itself, the crop that grows in paddies and produces the grain.
稻 combines 禾 (grain plant) with 舀, which likely contributes the sound and originally depicted a mortar for pounding grain, reinforcing the rice-plant meaning.
The left side 禾 is a grain plant, and the right side 舀 looks like a hand reaching into a mortar. Picture a rice plant being harvested and pounded to separate the grain.
For トウ, imagine a tall rice plant growing in a tower of water: tower -> トウ, and the rice plant stands tall in the paddy.