There are some great examples of non-metal hinges, in what we might call a "peasant" category, in the junkpole
fence thread. One utilizes a chunk of
wood with a depression carved into it, which serves as the bottom hinge point. One concern was that the bowl thus created would collect
water, leading eventually to rot and decay.
I went out this morning to start a gate for the
fence around our garden, and lo and behold, there sat a brick in the very spot I needed the bottom hinge.
The inside (hinge side) post of the gate was whittled on each end using a chainsaw, resulting in a crude sharpened-pencil point at top and bottom. The bottom point was stuck in the middle hole of the brick, which was anchored with a short piece of rebar that was bent into what amounts to a giant
staple. (See last photo.) The top point was inserted into a depression in a small chunk of wood (made with a 1/2" drill bit, wiggled around to expand the hole size), which itself was screwed to the adjacent walnut tree (see second photo) which serves more or less as my hinge post. The gate basically floats between these two hinge points, so that it can be lifted slightly to open; when closed the 'latch' end of the gate simply sits on the ground.
As is evident in the first photo, only the frame of the gate is completed; I'll add the uprights (1x2 lumber) shortly. The entire thing is made of eastern red cedar.
I'd love to see other similar gate hinge ideas that don't require purchased materials, or specialized metal- and/or wood-working equipment.