Why Wash Your Produce?
Well, the short answer is that you may not know where it has been, and even if it's from your yard, it's dirty - it's just a good practice. Dirt and harmful bacteria and fungi are no match for some running water and a good brushing.
If you live in or visit Hawai'i, there are other considerations, like Rat Lungworm Disease. Here's a link that will tell you all about it: