Wood chips are a great versatile resource. You can spread them over a corner of your garden for children to experience a different tactile surface for walking and jumping. You can make an outdoor sensory area of wood chips bordered by logs, with heaps of seashells and pieces of old brick or rocks, where children can pursue their imagination in peace.
If your chip pile is deep, you will see total large-motor involvement and role play. Some children will be digging and transporting, others will be cooking and stirring... They will happily return to this activity day after day, and it will only deepen and intensify over time. Meanwhile, there's that tangy scent and connection with nature.
Best of all you shouldn't have to buy them. If you don't have a tree-surgeon friend, you can always contact the road-works people. What a fabulous resource for free!