Nance (Byrsonima crassifolia). The plant itself is a tree which has little yellow fruit about the size of a marble. The fruit has an acrid, buttery smell. They can be eaten raw if you like the taste, although they´re more commonly placed in a bottle and drowned in rum for as long as you can imagine, which makes the taste a bit more bearable.
Not to be confused with Uchuvas (Physalis peruviana), which are also yellow and about the same size, but they´re tart and they don´t smell.