Summer-flowering pollinator plants are easiest to find and easy to grow. Most thrive in the sun. In my garden, the most popular native plants for bees for summer are anise hyssop, mountain mint, milkweed, culver’s root, ironweed, joe pye weed, and blazing star.
Popular non-native perennials include: lavender, Calamintha nepeta ‘Blue Cloud’, and Scabiosa.
Annuals for summer
Annuals can help fill in your garden while your native plants are establishing. They grow quickly and bloom over many weeks. A few that I’ve tried that bees and butterflies enjoy are Brazilian verbena, Pinwheel zinnia, ‘Lemon Queen’ sunflower, and Bees’ friend (Phacelia tanacetifolia).
Grasses can be used for texture and to tie a design together. Prairie dropseed and little bluestem are good companions for other low plants (2 feet tall), Switchgrass is about 3-4 feet tall with has fine, fluffy seedheads.
It is fascinating to me that native grasses can have such long root systems, measured in feet and not inches. For instance, switchgrass roots can reach a depth of 10 feet. As a result, grasses and other prairie-type plants help store a lot of carbon in the soil. See this National Geographic article Digging Deep Reveals the Intricate World of Roots about the incredible root systems of prairie plants.
Small Skipper butterflies use a variety of native grasses as host plants.