When small items such as seeds are being photographed, it's fairly common to place a common item near them to give a sense of their size.
If you are dealing with a bit of Poison Ivy, particularly on the hands or forearm area, quick and intense temporary relief can be had by running hot water (as hot as you can stand it without burning yourself) over the affected area. The effect won't last a terribly long time, but the level of relief is unmatched.