glutinous rice
糯 centers on a specific type of sticky rice: glutinous rice, used in mochi and similar foods.
糯 combines 米 (rice) with 需, which likely contributes the sound and may relate to softness or stickiness. The exact historical development is uncertain.
The left side is rice 米, and the right side 需 looks like rain 雨 over a soft shape 而. Imagine rain making the rice soft and sticky, turning it into glutinous rice.
For ダ, picture a sticky rice dumpling that is so heavy it goes 'da!' when dropped: da -> ダ, and the glutinous rice sticks to the floor.