Plants vs. Zombies: Battle for Neighborville

After completing the first mission with Major Sweetie, you have to find three items of Cool Swag for the Lawnmower. This quest will have you collect the Cool Bling item for the Lawnmower. To start, find Tenderleaf the Acorn on the map. Complete the quest and the achievement should unlock.

This is a story-based achievement, as such it cannot be missed.