Leaves have a Carbon to Nitrogen ratio, C:N ratio, of between 40 to 1 and 80 to 1 which means that all else being equal the bacteria will get busy and digest them. Often, if those bacteria are real active they will generate heat while doing that.

mean...
I've had piles of leaves and bags of leaves for months n months n don't think I've ever had them truly heat up on their own.

When I layered them with grass clippings, they got real hot, though.

As far as worms go, those bags of leaves are awesome for attracting worms. In fact, I used them to load my worm box (on several occasions I stopped counting when i found 100 worms under my 5 bags)

I harvest night crawlers for fishing from under my leaf bags. Huge nightcrawlers as well as man smaller ones. Worms definitely love leaves.

I use mainly three kinds of leaves -- oak, sweet gum and maple; after they fall off the tree. Oak leaves do not 'heat up' i.e. self compost. Sweet gum and maple leaves will develop heat in the compost pile; even more with a bit of fresh grass when the collection is done with a bag mower. Some turning and watering will be necessary in the following days and weeks.

Maybe the simplest compost mix is just to shred and collect a good grass and leaf mix in the fall. Might be from September to November, depends on the weather and moisture.
There is often a week or two when things just perfect for a natural mix. Say things are dry in October and a one inch rain knocks a quarter of the leaves down. I might wait two days for the leaves to dry partly, and the grass to green up a bit. Then I get out the push mower, take off the bag and cut the grass fairly short blowing the stuff in one direction. When the stuff looks short enough, I put the bag on and collect the material for the compost pile.

When nature helps out like this, no reason to collect paper, coffee grounds, etc. that month!

robertz6,

that's my favorite time of year, copious amounts of leaves mixed with still growing grass piled as high as i can get them.....at the moment my compost pile has cooked down to the point i'm about to start using it, probably the earliest in the season i've ever had finished compost

peace, love, and good dirt,
allen456

I use mainly oak leaves for my roses, oak leaves if they get wet will eventually heat up.
I reuse, rebag, the leaves in the spring for potatoes and use up bags as needed to keep the potatoes covered. I do not try to get them wet but even the heaviest plastic bags get holes in them and rarely do they not eventually get wet inside.
When I empty the leaves on the potatoes, I spread them by hand, the leaves on the bottom of the bag will often feel warm.

Right now I have one bag left, a fresh unused bag was used and last time I checked the leaves inside were dry and by the weight of the bag probably down on the bottom also. IF kept in this condition oak leaves will not heat but then I had some sealed bags of maples leaves from the neighbor I kept in reserve all winter and when spread out a month ago they also were dry and heat free.