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.
I spent the afternoon gathering the edible (and medicinal) pollen cones of Eastern White Pine (Pinus strobus). I visited a special grove of large pines which had some branches low enough to reach and were absolutely laden with bright yellow cones at the perfect stage of growth for foraging.