Redstone Berry

Redstone Berry is a first-obtainable plant in Rewind Rift in Plants vs. Zombies 2. She can be joined together to make a redstone fence, similar to Electric Currant and Icy Currant. However, unlike Electric Currant and Icy Currant, she can shoots redstone gem by tapping on her, and need to recharge overtime.

When she being connected by other Redstone Berries (like two or more), after being tapped, the others can attack zombies without being tapped.

Origins
Redstone Berry was based on strawberry, belonging in the Fragaria genus. Like Strawburst, in visual, she's presented as an upside-down strawberry.

Her appearance may based on Redstone Dust from Minecraft. Also, her ability may be a reference to redstones can trigger trap blocks when turned on by a lever/button/pressure plate/redstone torch.

Her primary costume references Redstone Ore from Minecraft, while her secondary costume references Aphmau, a YouTuber that played the same video game (if you didn't count other video games).

Plant Food effect
When being fed by Plant Food, she can shoot loads of redstone gems and then recharges herself. When being connected by other Redstone Berries, they will shoot a lot of redstone gems (following with herself), like Puff-shroom.

Pepper-mint's effect
When boosted by Pepper-mint, she will absorb from 20 DPS to 80 DPS per redstone gem. Also, her redstone fence can be powered to damaging zombies when they're stepping on it.

Trivia

 * Unlike Strawburst, she appears to be hidden underground. However, real-life strawberries don't live underground, they growing on strawberry trees.
 * This may be a reference to Minecraft as well, which is the fact that redstones can be found in caves, aka underground.
 * One of her costume represents Redstone Ore from Minecraft.