Seeds seeds seeds

Hello! I have questions about growing from seed. I have never had a clematis plant and would like to grow one from seed. Is it difficult to grow from seed? I live in southern Ontario and clematis is quite popular here but I have never known anyone who grew theirs from seed. I also haven’t got the slightest clue where to get seeds. Every time someone gives me clematis seeds they are not actually clematis seeds but some other type of vine. Can anyone help me with this? Maybe point me in the right direction for purchasing seeds?