Identifying little flies is not something I can do so I reached out to BugGuide for help. It's in the Family Empididae, the Dance Flies. They get their common name for bobbing around in a swarm in sunlight over an "environmental marker". You can create your own artificial marker by putting out a white sheet or towel on a sunny lawn. In a short time, flies will gather in the air above it. Move the towel and the flies will soon follow. Often, the purpose of such swarms is as a gathering point for mate selection.
Here's my post and the reply I got: https://bugguide.net/node/view/1816845#3022034 (It was Yurika Alexander who helped me. Check out her brief bio: https://bugguide.net/user/view/38836) From her reply, I followed a link to the genus Rhamphomyia and the species group R. scolopacea: https://bugguide.net/node/view/301040 Finally, at the genus Rhamphomyia page I learned that there are 150 named species in North America and at least 400 known but as yet undescribed species. Interestingly, the one I photographed seems to be a species that specializes in Dwarf Cinquefoil ((Potentilla canadensis) as most of the other photos of it are on that flower.