bud (plants, mushrooms not yet opened)
蕾 centers on a plant or mushroom in its early, unopened stage: a bud. It captures the moment just before blooming.
蕾 combines the grass radical 艹 with 雷, which likely provides the sound. The exact historical development of the meaning 'bud' from these components is uncertain.
The grass radical 艹 sits above 雷 (thunder). Imagine a thunderstorm's rain coaxing a tiny bud to emerge from the grass.
For ライ, picture a bud lying in wait under the grass, ready to bloom: lie -> ライ.