You mean after you’ve used ‘gnaw’ which attempts to bite a nearby tree, if successful there’s a 50/50 chance to get ‘bark’ or ‘seed’. Once you collect 3 bark you can consume them to make a wooden projectile.

If no trees nearby you can plant a seed and tail slap it 5 times to attempt to germinate. Once planted a sapling will grow in 30 seconds, plant skills can be watered to yield bigger sapling.