Edit. After Black September's assassination of Israeli athletes at the Munich Olympics in 1972, Prime Minister Golda Meir okays a black-box operation to hunt down and kill all involved.
Yellow pollen is produced by evergreen trees, primarily pine trees, including spruce, true cedar trees, fir trees, larch and hemlock. Although yellow pollen looks like it could cause an allergic reaction, in reality it does not trigger allergy symptoms at all. It can stain the skin and clothing, however.
Using a paintbrush or something soft, rub a flower of one paw-paw tree to collect pollen. Then proceed to rub a flower of another tree. *Note: You cannot take pollen from one tree and use it on the same tree! Each individual flower will only accept pollen from a flower from a genetically distinct individual tree.