A hot tip for a day trip is Karls Erdbeerhof (Karls strawberry yard) located in Rövershagen near Rostock. But there is far more to discover than strawberries.
The Erdbeerhof is designed like a farm with a lot of strawberry fields around it. Of course you can buy strawberries there, but also all kind of strawberry creations like strawberry cake or strawberry shake. They got a nice cáfe there where you can enjoy all these creations right there.
For the children they got a big indoor playground called “Tobeland”. From time to time there are big events and even in the winter, when there are usually less strawberries, the Erdbeerhof knows how to catch visitors i.e. with the “Eiszeit”, an exhibition of ice sculptures.
You might also have a look at the world’s greatest ceramic jug exhibition. But be careful not to break any of these.
But they also have a nice restaurant where you can have lunch (even without strawberries) and I recommend the Sunday brunch to you. For 15,- € you can chose from a metres-long buffet and you can eat as much as you want. After paying once you can enjoy yourself on the whole farm and if you get hungry again, you simply come back and grab some food again.
During good weather I recommend you to go by bike from rostock, the trip is about 15 km long.
But there is far more to discover than the things I mentioned here. Just go there and explore it for yourself.