So I'm a writer, and as a bit of a challenge to myself I'm working on a story involving a society where there are no available trees. In some cases there are alternative resources that can be used where wood would be (coal for fire, bone for handles), but one sticking point I keep hitting is the spear. Basically every society on Earth developed the spear at some point, but did any society ever develop spears made of something other than wood?
The short answer is yes. All of the examples I've seen use iron/steel hafts. Excluding modern fantasy weapons, the three main groups I've seen are:
Late 19th and early 20th century European cavalry lances. These typically use a tubular steel haft. Example: https://collections.royalarmouries.org/first-world-war/type/rac-narrative-85.html
Indian iron spears. Most examples are relatively recent, 18th century and later (but most surviving Indian weapons of most types are also similarly recent). Many of them are cavalry lances. Examples: https://www.metmuseum.org/art/collection/search/24425 https://www.metmuseum.org/art/collection/search/30755
Tuareg cavalry lances. Example: http://www.swordsantiqueweapons.com/s803_full.html
The above are all "full length" spears, long enough to be used as cavalry lances. There are also short all-steel javelins, mostly from the Middle East and nearby regions (Persian, Ottoman Empire, Russia, etc.). Example: https://i.pinimg.com/originals/41/23/fa/4123fa92b5b569a72d4e6a94c18ab4a5.jpg (from Stone's Glossary).
If one was to be pedantic, one could also include bamboo and rattan hafted spears, since neither is technically wood. Both are common in regions where bamboo and rattan grow. Bamboo is sometimes split and the pieces used to make a solid laminated haft (as opposed to a hollow haft of as-grown bamboo).
Other materials can be used, but will often need to be straightened and/or made into a multi-piece laminated/spliced haft. Some suitable materials are antler, bone, horn, and baleen (whalebone). Bone is perhaps the least suitable, being the most brittle. Antler, horn and baleen can be shaped by soaking and bending/straightening into the desired shape. All of these materials have been used for hafts for tools/weapons such as axes, adzes, and knives, and for other weapons. All of them have even been used for making bows (in regions where wood suitable for bows is not available, such as the Arctic) - these bows are typically "cable bows", where the elasticity comes from a sinew cable along the back of the bow. Some cable bows: https://commons.wikimedia.org/wiki/File:Inuitbows.jpg (I can't identify the materials from the photo). A bone bow: http://www.virtualmuseum.ca/edu/ViewLoitDa.do?method=preview&lang=EN&id=11810
