My Yard, My Neighborhood (excluding trees and bushes)

April crocus, Dutchman's breeches (native woodland), grape hyacinth, Glory of the Snow, pulmonaria (lungwort), dandelion, Virgina bluebells, yard violets, daffodils, tulips, bleeding heart, pasque flower, wood anemone

May wood hyacinth, creeping phlox, woodland primrose , big white trillium, wild geranium, lilies of the valley, jack-in-the-pulpit, swamp buttercup, field mustard, iris, Jacob's ladder, merry bells, wild columbine, blue flax, mayapple, shooting star, oriental poppy, bladder campion, yellow sweet clover

June spiderwort, peonies, wave petunias, geraniums, tuber geraniums, forget-me-nots, various wildflower daisies, yellow loosestrife, bellflower, wild carrot (Queen Anne's Lace), evening primrose, various lilies, roses, Russian sage, fleabane, chamomile, black cohosh, solomon's seal, red clover, yellow wood sorrel, coreopsis, yarrow, motherwort, wild bergamot, harebell

July white campion, milkweed, chickory, liatris, astilbe, hostas, black-eyed susans, bee-balm (menarda), purple coneflower, mallow, lamb's quarters, American oregano, golden alexanders, wild parsnip

August lady's thumb, mums, marigolds, starry campion, blackberry lily, common burdock, tansy, goldenrod, thistle, toadflax, bindweed, sedum, prairie blazing star, red milkweed, common milkweed, spotted Joe Pye, boneset, butter-and-eggs, sunflower, orange jewelweed, phlox, roses (again), ragweed, meadow rue, dusty miller

September white heath (?) aster

Online Resources
Aquatic and Wetland Plants and Invasive Plants
What's Blooming? -- Common Roadside Plants of Wisconsin
Wildflower Identification
Wisconsin Native Plants for Rain Gardens