Renee,
Don't be frustrated! You are doing good.
On the link below is a good pic of Catharanthus roseus(annual vinca) seed pods. They are not ripe in the pic. They must dry, but at least you know what to look for.
A tip for searching is to use the proper latin name for the plant. Searching "annual vinca seeds" will not yield as good of results as "Catharanthus roseus seeds".
I'll make another post to Coneflower seeds.
Remy

Here is a link that might be useful: {{gwi:243459}}

The link below is a page from The Seed Site. The Seed Site is an excellent resource for seed savers.

Here is a link that might be useful: Echinacea Page on The Seed Site

This next link is for the Annual Alyssum page on The Seed Site.
Remy

Here is a link that might be useful: Lobularia maritima on The Seed Site

Thanks so much, Remy, for your informative responses! I never knew the proper names for the plants in my garden but will now find out and make a list.

Best regards,
Renee

Hi Remy,

I just went outside and was finally able to see the vinca seeds!! How do I know when it's ok to pick them? For the allysum, do I need to wait until the flowers turn brown?

Thanks so much in advance for your advice.
Renee