Almost certainly
weather balloons. They often get launched in groups of two or more, and can be very reflective. My youngest daughter actually spotted three in the sky a couple weeks ago from our backyard...”Daddy, what are those? It’s too early for stars”, she said!
I actually broke out my telescope and we were able take a closer look - they sort of looked like jelly fish, but you could also see the radiosonde/weather equipment suspended beneath it and a couple of strobe lights flashing with the high magnification. Pretty cool sight, and I was proud of her for spotting them! We ended up calling the neighbors and their kids over to have a look too. Ours moved noticeably, but depending on the upper level winds, they could appear somewhat stationary as they gain altitude.
Edit: Just found this link, which shows a picture of exactly what my daughter and I, and the neighbors saw: https://www.wral.com/google-internet-balloon-passes-through-triangle/19187640/?version=amp. So you may have seen a weather ballon, or you may have seen the Google “Loon Balloon” Project!
https://en.m.wikipedia.org/wiki/Loon_LLC
https://loon.com/