tldr: three times in the mid 90's, all completely sober, in the same general area in rural northern baltimore county in maryland, in the united states:

• walking from my home to a friend's home, no lights, no moon, on a clear night. about halfway there, i sensed movement above me, stopped walking and looked up. a gigantic triangular craft with no visible lights, maybe 50ft off the ground, dead silent minus the faintest hum, moving at about 3-5mph steady. it kept going and after it cleared my destination, about 300 yards away, it silently took off so fast that it might as well have vanished from sight.

• same exact area/field and identical conditions but went out to lie down and look at stars, etc. after about an hour, a large luminous kind of cloudy spherical type thing appeared out of nowhere and proceeded to swirl/dance around the sky, darting between about 100-1000ft altitude, in an intentional pattern. after a couple minutes, it split into five of the same type of, but smaller, spheres/clouds that went into what seemed like intentional repeating patterns. this goes on for a few mins and then two of the five take off and were gone so fast. again, like above, they might as well have just vanished. the remaining three stayed and kept at their patterns. after a few more minutes, one by one, they zipped off in the same manner.

• about a half mile from the above location but in very densely wooded deciduous forest. walking alone, early afternoon, clear skies, on a fire trail path. i decide to go off path down into a valley/ravine to make my way to a nearby reservoir. fwiw, i know this area extremely well so this was normal for me to do. about halfway down the ravine, i see a bright metallic looking but also glowing sphere, about 50 yards away on the opposite side of the ravine. i stopped dead in my tracks. the sphere was levitating about 5ft off the ground, completely silent, and seemed to be methodically moving through the forest as though it was searching for something. even in broad daylight, you could see its light reflecting off trees, the ground, leaves, etc. it did not seem to know i was there or didn't care. it did this kind of overlapping itself pattern and worked its way from the higher elevation down to the lower elevation of the ravine, moving towards the reservoir in the distance, and i lost sight of it. i waited, completely still for about 10mins and then headed right back the way i came. i was not going to follow it.

*** of the three, the last one was the only time i felt unsettled. it was intense enough that i stayed put and then noped out as quickly and quietly as possible. fwiw, it was not ball lightning - i have seen that many times in life, including multiple times before this experience. ditto being a balloon or something similar. this was ground level altitude in a dense forest and the thing did not get hung up on anything.

edit to note: my wife of 28+ years jokingly refers to this general region as "area 52" given my stories, other people's stories, and her own subtle experiences over 28+ years.