After seeing a helicopter & A10, a formation of about ten winged, but vertical, objects glided silently through the air over my cove

A low-flying helicopter, maybe 250ft off the ground, circled around several times south of my house about half a mile. Not more than a couple of minutes later, I heard an army jet of some kind overhead. I looked and after seeing 2 strange jet streams that were very short and tightly curved and quickly dissipated, I saw an A10 Warthog make about three circles, the last of which crossed over my property, West to East.
As the A10 flew over me West to East, I saw around ten silent objects fly by in formation behind my house and disappear into the tree-line. I grabbed my phone so that I could video them when they emerged on the other side of the tree-line, but they never did. I have limited observational experience, but I fly drones, so I'll do my best. The objects had a brown body and black wings. At first, I thought it was a flock of birds. But they were big for birds, as big or bigger than birds of prey, such as eagles. And that's assuming they were close by, maybe a few hundred yards away flying over the cove. And I've never seen birds of prey fly in formation like thes were, nor in a flock. Then the sun glinted off of one of them, so I figured they were metallic. Also, they flew by horizontally, yet their wings were perfectly vertical, which would give them no lift. Again, they were perfectly silent.
My best guess for size and distance is that they flew over our cove in Lake of the Ozarks at approximately 150 ft AGL, possibly with bodies the size of basketballs or beach balls and wingspans of maybe 4 to 8 feet. That is my best guess, sorry I can't be more exact. They had a slight bobbing motion as they flew by. I saw them for the span of only a few seconds and possibly 500 horizontal feet. I estimate their speed at 50 to 75 mph.
I live about 40 miles from Whiteman Air Force base and about 60 miles from Fort Leonardwood as the crow flies. With the fact that these objects were preceded by other military air support, possibly scouting for them, I wonder if they were some type of experimental drone that the military is testing. But they didn't exhibit the properties of typical modern aircraft, so I am reporting it here.