Plants that come up every year are perennials and in the site you have there are too many options to list. But you can try Sweet William, pinks (both scented), aquilegia which will self seed and foxgloves. Though the latter are technically bi-annuals they self seed so you will still see them each year and they will grow in sun or shade.
The best thing to do is get a book on perennials and find plants that attract you then see if they can be grown easily from seed.
Personally, I don't do very well with seeds (too impatient, I guess) so prefer to buy plug plants and pot them on but good luck.

Perennials. Consider the type of soil they will be grown in too; moist or dry, sandy or clay..etc. As far as easy to grow from seed, Allium, Dianthus and Primrose come to mind and I'm sure other members will give you suggestions too. One other thing, it is almost June and it might be getting too late to start planting from seed to get these plants well established by the end of the season.

Why didn't I think of saying that?

It's fine to sow perennial seeds in pots or trays at this time of year. You can grow them on in successively larger pots and plant them out either in the autumn or next spring. It's a bit late to expect flowers this year.

I do better growing them in seed trays then potting on......my Gallardia did well.....

Thompson and Morgan give a sowing and cultivation grading which is reasonably accurate. First find perennials you like, then check their rating E/E means easy to germinate, and easy aftercare. Then progressively nurture through the pricking out, potting on and growing on stages, never letting them 'check' by filling whatever stage they are at with too tight a rootball, and plant out either in autumn, or next spring. Care and attention should see them filling at least 1 litre size pots by end of year, which makes them more likely to succeed when you plant them out. Gailliardias, hollyhocks, achillea, malvas, delphinium, are all pretty easy. Lupins too, but presoak seed overnight.
You will end up with more than you need, but try sharing and swapping with friends.

thank you everyone who offered advice.. you have given me lots to think about and I appreciate all your help. When I have planted I hope to take a few pics to show on here