For the past 45 years or so, I have been mowing the lawn and leaving everything alone. You know, put it back into the yard. Recently, I decided to buy a bag and frame for my mulching mower and see what I could produce, since I am now growing in raised beds. I had no idea just how fast the bag will fill up! Luckily, I also have a huge area that I never raked the leaves, so this is the perfect source for carbons.
The first pile was still holding out at 120 degrees, even after 18 days.
The second is still cooking, but at only 36 hours in, was well into the hot zone.
What's in the bag is what I sifted from last year's pile that went cold. I have four, 38# cat food bags full of it ready to go. The stuff that didn't make it, went into the hot pile to break down again.
If you have a lawn, you have everything you need to make your garden grow.