Team Lava offers surprise/gift boxes. They are located under the expansions tab under design view. They normally cost 24 gems and they are themed. You take a chance at buying them because you won’t know what you get until you buy it.
I bought two of them in Restaurant Story – I got a mermaid statue in one, and a really cool waterfall in the other. They are fun but they are a gamble! I've only bought the Magic Shell ones below. Those seem to give water themed prizes.
Mystery Boxes are located under the expansion tab and cost 24 gems.
This friend of mine took this screenshot for me. If you store your gift box items, they will show up under your design tab in the appropriate categories - similar to below.
To buy one click on it, and a window will pop up telling you what prize you got and under what tab in design you can find it. Go to that tab, then place it somewhere in your restaurant/bakery.
Now if I click on the decoration tab I see my mystery item I bought above. Click on it to place it in your bakery/restaurant.
Other options to get cool stuff is available through pop-ups when you open the game. They are timed deals so they are only available for a limited time.
This is an example of a deal where if you purchase one of the gem packages, you get the stained glass window too. You can ONLY get the stained glass window through this deal. So if you see future deals like this, make sure you purchase through these screens only.