Myopa vesiculosa, maybe? Additional photos available if they might be helpful. On Cornus Florida, back garden.
Howard County Conservancy gardens and trails- locations approximate
Swarming the coast and climbing on everyone
iNat's suggested ID
These flies appeared to be feeding on an invertebrate, possibly dead, that was partially buried in the beach sand.
Many on a rocky jetty, doing mating displays with wing waving. Last photo = habitat.