There was a recent asbestos scare up in Montana recently (story here). Turned out to be nothing more than just that, a scare, but reminds us of an important point.
What's in your mulch, wood chips or whatever else you're putting on and/or around your trees, shrubs and grass? Are you going the cheapest route, or are you confident that it's a high-quality product that isn't going to do more harm than good?
Products such as mulch and fertilizer may seem like rather straightforward products that require little research or thought; just buy a bag and toss it in the back of your truck. But have some fun and make your supplier work for the sale by asking them to prove that their product is top of the line.