I pick up bags of shredded computer paper from the commerical area nearby on their recycle pick up day. It's just sitting at the roadside.
It makes great chicken litter too
It looks a little odd on the garden as it's so white and people ask me what that is when they see it. It makes good, light mulch. Paper is a wood product, however, so will use up nitrogen in the soil as it decomposes so make sure you put some manure in there too.
You can usually get free manure by the truckload from horse farms, etc. Just make sure it's old and composted.
I pick up yard waste bags from the curbs in the fall. They are usually full of leaves. i have a lot of my own leaves to use too but these are already raked for me