It was first seen in a Twitter message by EA. It was scrapped from the first game, but it later appears in Plants vs. Zombies: Garden Warfare 2 as Rock Pea.
Peashooter's and Sunflower's Rooted abilities
In the first trailer, the rooted abilities of Peashooter and Sunflower looked different from after the game's release as there was no dirt surrounding their roots.
The Zombot was seen in an E3 2013 Demo of Plants vs. Zombies: Garden Warfare. Its model was never used in the final game, and is likely an unused boss. It does appear in the Z-Tech Factory and Zombopolis in Garden Warfare 2.
Design a Peashooter contest
These are the top 5 designs that PopCap was deciding to choose between when the Design a Peashooter contest was going on, Out of these, the Plasma Pea became the winner and was added to the game.
Bosses in Gardens & Graveyards
In one of the trailers, a Gargantuar is seen running to crush plants on Driftwood Shores. This might have been a mistake, or it was scrapped. There is also a Yeti seen near the tree garden on Main Street.
The Bling Chomper was one of the original Chomper variant concepts, but it was scrapped for being too underpowered. It is unknown why it was considered weak. The Disco Chomper from Garden Warfare 2 is vaguely similar to it.