We really should leave the leaves. That's right, the forest floor with its carpet of leaves serves multiple functions from mulch to plant and insect food.
It's highly unlikely you are going to clear out a forest, so it's okay to take some for your garden for mulch and plant food, but don't gather all the leaves from beneath a lone tree or row of trees.
Come autumn or fall, deciduous trees and bushes shed their dying leaves. Put a deep layer of these leaves of 15-20cm (6-8in) or more on your garden and it's called leaf mulch... a great mulch to hamper weeds, retain moisture and help keep soil temperatures even.
As leaf mulch decays it turns into leafmould — a rich, dark soil conditioner and light fertiliser.
Leaves can be made into leafmould separately from the leafmulch on top of your garden. You simply pile up the fallen leaves in a sheltered spot and leave them to take their time to turn into leafmold, usually by the cold compost way.
This process can take one to two seasons if the leaves are uncovered, and almost half the time if covered snugly. It can then be used when needed, usually in spring, added on top of the garden or lightly hoed or raked in.
And to speed things up, you'll get faster leafmold if you put the leaves through a shredder first.
Or if you don't have a spot to heap up with leaves, or want a tidier and usually faster solution, you can stuff wet leaves into old sacks or used, dark plastic rubbish bags, then tie the tops, poke a few air holes through and leave to quickly rot for use the following spring.
Compost loves leaves — Leaves make good brown (carbon) layers added to your compost pile or bin inbetween layers like kitchen scraps and other green (nitrogen) stuff.
What about other no dig garden materials? There's a pile of information on squidgy, slimy, messy, mucky and ever so beautiful other stuff from seaweed to mulch and manure here: No Dig Materials