Wattles and many of the pea flower family produce pods which open up as they mature. The seed is released and falls onto the ground. The best time to harvest seeds is when the pods are just starting to open up and the seeds are still attached. Make sure the seed is dried well, then store it in tins or jars in a cool place, away from sunlight. The plants which evolved in Australia have special features because of the climate and soil type.
Australian soils are very old and are low in mineral nutrition content.
Australian plants have evolved various means of coping with poor nutrition. Reason One - Conserving natural heritage. Much of our natural bushlands and forests have been destroyed in the name of progress and development, with the result that many species are extinct or endangered. Reason Two - Local plants are suited to local conditions. An enormous range of species are available to suit most parts of Australia.