Here's a list of plants that readily self seed for me in my garden. I either leave them where they are or dig them up to plant them somewhere else in the garden. I also give them away to friends and co-workers, who always appreciate a good free plant.
Plants That Self Seed
Rose Campion - Blooms all summer long with pretty woolly silver-grey foliage. Great for filler in floral arrangements.
Indian Summer - A Black-eyed Susan that re-seeds every year, blooms all summer long with large 3-inch blooms.
Perennial Cornflower or Perennial Bachelor's Button - Some say it's a pest because it can get aggressive, but I love the blue flowers.
Hardy Geranium - Unusual foliage with dark markings, and delicate dark flowers that have a vintage quality. This is one of my all-time favorites.
The common name is Beardtongue but I mostly think of it by its Latin name, Penstemon 'Husker Red.' It's a US native and was named Plant of the Year by the Perennial Plant Association in 1996. Shown here depicts the beautiful dark foliage and as well as in bloom.
This Brunnera has the prettiest shade of blue flowers in the spring. You definitely may need to keep an eye on this one so that it doesn't take over in the garden. Not to be confused with Myosotis sylvatica, commonly known as the forget me not flower which is also a heavy re-seeder.
I hope I've inspired you to add a couple of these beauties to your garden if you don't already have them. I think it's so fun to see them volunteer in different spots in the garden. I get a special thrill when I notice them and realize they are not a weed.