wild strawberry
莓 centers on the wild strawberry plant and its fruit. The meaning is specific to this small, ground-growing berry.
莓 combines the grass radical 艹 with 每, which likely contributes the sound. The character is used for the wild strawberry, a low-growing plant.
The top 艹 suggests a plant, and the bottom 每 looks like a mother plant with little berries hanging down. Picture a wild strawberry plant spreading low across the ground.
For バイ, imagine buying a basket of wild strawberries at a market: buy -> バイ, and the basket is full of the small red berries.