unpolished rice
粡 centers on rice that has not been fully processed: unpolished rice, still in its natural, coarse state.
粡 combines 米 (rice) with 同, which likely contributes the sound トウ. The character is used for unpolished rice, but the exact historical development is uncertain.
The left side is 米 (rice), and the right side is 同 (same). Picture rice that is still the same as it was when harvested—unpolished and natural.
For トウ, imagine a toe accidentally stepping on unpolished rice: toe -> トウ, and the rough rice reminds you of the reading.