scallion, small onion
茘 refers to a scallion or small onion, a type of allium plant with a mild flavor.
The origin of 茘 is uncertain. It visually contains 艹 (grass) and 刕, but the historical development is not well documented.
The top 艹 suggests a plant, and the bottom 刕 looks like three blades. Imagine a scallion with blade-like leaves sprouting from the ground.
For レイ, picture a scallion laid out on a plate: lay -> レイ, and the scallion is ready to be chopped.