I believe this is a Sea Nettle (Chrysaora quinquecirrha) but that name was not found on iNat.
This Cannonball Jelly (Stomolophus meleagris) was found washed up on the North Myrtle Beach shoreline in South Carolina.
In intermittent tidal lagoon. Dead. Photos on both upper and lower sides.
Saw 20-30 of these jellies on the beach.