It's the night before yard waste pick up here. I look for pillow soft looking bags. That's how you know they are filled with something consistent whether it be leaves, grass, top soil, or a mix. The focus is on leaves but the grass is gold. In urban areas like where I live, the grass clippings are replacement for manure that has to get mixed with the large amounts of carbon.
It's been a couple of weeks since I began a new Plant Nation Garden Model in a highly urban location where I have yet to see it be done before.
If you can find a source for carbon, obtain it. Maybe your city will bring it by the truck load (mine did once) maybe they offer piles of fine and course mulch free for pick-up (get your five gallon buckets.) Sawdust from woodshops.
One you and I both have is yard waste pick up. That day of the week everyone puts out what they've collected from their yards.
Sometimes, you get rewarded with an awesome find. This week an enormous dragon fruit plant was discarded. I plan on planting it but it is also easy to sell it in parts or do both!