My barn and silo are full?

Even though everything is full there are still things you can do. You can still fill the machines to produce item. You see only 9 but it will allow you to stack up to 99 items on the floor. If you fill the animal feeds, sugar mill and popcorn pot it will free up space in the silo. If you produce stuff like dairy or cakes it will use products from the barn so you could keep this up for a while.

Use the free advertisement every half hour to make an advertisement so people will eventually come and buy stuff. If not Greg will buy the items that have been sitting there for quite some time. 

You could even use diamonds to get an extra advertisement in the paper or trash the item from the shop however you will not get it back.

 Add a lot of friends in Game Center and they can find your shop even when you aren't advertising.