In the plant reproductive process, seeds form inside the ovary (which becomes the fruit we know) after pollination. There are some plants where it appears that the seeds are carried on the outside of the fruit, but this simply isn't true.
Contrary to popular belief, the sweet red flesh of the strawberry is not the fruit. It is a part of the flower called the receptacle that is located below the ovary. The receptacle swells to attract animals so that they will eat and scatter the true fruit. These are the small yellow seed-like parts, which is a dry fruit called an achene.
On the tree, it appears that the cashew grows on the outside of a fruit that looks like an apple. However, this is another case of the receptacle swelling to promote the true fruit, which are called drupes. Similar to stone fruits like nectarines and cherries, the cashew is the pit inside a shell.