I'm a landscaper, and I would be very nervous about getting any clippings from a landscaping company. Anyone who is willing to pay someone to mow their lawn (especially in this economy), is going to be picky enough about their lawn to have it sprayed for weeds, fertilized with chemicals, etc...Landscapers love to do this stuff because it is good money, and not too hard work. I use only corn gluten meal on my lawn, but I am an exception. Finding a place that can give you old produce is your best bet. Weeds are also good if they don't use chemicals--my chickens love them better than lettuce! If your neighbors have gardens with unpicked cabbage etc... that have gotten wormy that is a great find.