Plants vs Zombies Garden Warfare 2 has a lot of collectibles and secrets. Golden Gnomes are among the things you can collect, but there is more to it.
If you collect at least 10 of these Golden Gnomes, you gain access to a secret area in the sewers. There are 54 total Golden Gnomes you can collect, but I'm only going to show you 10 of them since that's all you need to get to the secret room. If you want more help with the game, check out my Beginner Tips and Tricks.