(Apologies to Kristen whose submission was lost until today!)
The strawberry guava was purchased from Gurney's online, and the lychees came from pits from fruit I ate. The calamondins come from the seed of a single ripe fruit that fell off of an expensive plant at a nursery (I asked if I could take it home with me). If you don't find a stray calamondin fruit, kumquat seeds grow just as fast. The avocado pit was donated by a friend.
This is a very dark corner, but the plants grow fine.