I'm lucky to live where I can get compost/mulch with some horse contributions, mixed with bark and peat, and aged enough to smell good. The local supplier is Wilby's (note to self.) I put down about two inches per year. It's kind of expensive but it does feed the soil, making for lots of very happy earthworms.
I received coconut coir bricks with an order of apple trees. These bricks need to be soaked in water for about 30 minutes, and because they float, they need to be turned and chopped once or twice while soaking. It's probably a good way of getting moisture-retentive material into a planting hole, since you can dig the hole, fill with water, and soak the brick in it.
Not sure how to use bricks to mulch a large area. All the forms of coir I've encountered have been compressed, so soaking is required. I bet one could toss an occasional brick into a (largish) composter to bulk things up; not sure if one would need to add water at the same time; I suppose it might depend on how wet the compost is.
