From Brotato Wiki
Killing a tree spawns a turret
Item
Pocket Factory is an in-game item that can be bought from a Shop or can be found in a Crate. Most Items modify the Stats of the player, and some of them provide additional effects.
Unique
Pocket Factory is a unique item. Only 1 of each unique item can be equipped, and it will then no longer be offered in the Shop, and no longer drop from loot crates.
Pocket Factory
When you have Pocket Factory, a 
Turret will spawn every time you kill a Tree. The turret spawns next to where the tree was. You can increase the amount of trees that spawn by buying more 
Tree items. Over the duration of a wave, this can result in quite the number of turrets.
Pocket Factory counts as having 1 Structure for effects such as Armor for 
Streamer or negative Engineering for 
Lighthouse
Unlike other Structure Spawning items, Pocket Factory does not grant any additional Armor to Streamer.