You will need to be Facebook friends with people in order for them to show in your Friends List. The friends system is controlled through "Budbook," the in-game tool that lets you sync your game to Facebook.
Once you've synced with Facebook, you will find that existing Facebook friends who also play Pot Farm: Grass Roots should already be there waiting for you! (Tap the Phone icon in the lower right hand corner of your screen, then tap the green/white "B" symbol - this will open up Budbook.)
If you have not already connected to Facebook, don't worry, the game will prompt you to do so. Once that's done, you will see that you have Floyd as a friend! Everyone in the game is friends with good ol' Uncle Floyd, and you can visit his dispensary through Budbook to see new items for sale on a daily basis. In addition, you should be able to see a a list of whomever else you are friends with on Facebook - they will be listed underneath Floyd in a scrolling list!
Another way to make Friends beyond those you already have on Facebook playing Pot Farm: Grass Roots is to check out our Fan Page Wall: https://www.facebook.com/potfarmgrassroots
It is a rad community, with lots of friendly players that will gladly add you!
Plus, you'll get all the tips and tricks that players are using to level up and enjoy the game even more!
There is also a Following/Followers option - this allows players to add others as friends without having a Facebook connection through Budbook! Currently, farmers are allowed to follow up to 10 other players, but can have unlimited Followers!
To Follow someone, simply visit their farm (either by searching for their Username or finding them via Floyd's List) and tap the purple "Follow" button (with a star-banner) at the top right.
Have fun with your friends!