Hmmm there are usually worms under deep piles of leaves maybe its too cold. You need to go to a forested area and look for these places where the leaves collect, there is usually black earth immediately under the leaves (created by the worms) on top of what ever soil clay or otherwise. Earth worms don't much like hard pan clay no deep leaves though unless there is that decent layer of top soil or humus , go to another area
Even hard dried out soil will have earth worms if you dig up a spade or two failing that you are very welcome to come and get some from one of my compost areas in the garden when I get back from safari sometime after Jan 2014.
I once unearthed (in a pile of leaves) a whole lot of salamanders, warty and crocodilian with bright red bellies. Another time a nest of freshly hatched bamboo vipers, they are incredibly cute and behave exactly like an adult all jerky and stiff striking left right and centre, they aren't born very green. Another time (you can see I rootle about in compost heaps a lot facinating places) there was a beutiful shrews nest with tiny tiny shrews.
Actualy I use the soil created under the heaps to top dress pot plants, I love gardening it keeps me fit and the gardener fat.
Not. She does all the hard manual labour I sort of direct showing by example.