Is it acceptable to just send a dried flower head or pod?
Ask your fellow trader for advice about collecting the seeds, or post a question to the 'Growing From Seed' forum. If the information you obtain still doesn't help you locate the seed, ask the trader whether (s)he would be content to receive the pods or flower heads. There are a couple of potential problems in sending uncleaned seeds. First, not all flowering plants produce seed, for example plants that were not pollinated or certain hybrids (any seed that is produced by the latter may also be sterile.) Secondly, pods and flower heads are more subject to mildew and rot than are properly dried and cleaned seeds.