There's a new book that talks about this. I hear about it over on the Somewhere in the Skies podcast, and I think it's this one:
https://www.amazon.com/President-Eisenhowers-Close-Encounters-Blake/dp/1645830381
There isn't any evidence for it, just rumours. But one of the things I remember from the interview was that the aliens Eisenhower allegedly met were the tall white type. And it was more than indicated that the small greys were some sort of machine, or clone, or android type or worker drone, without much independent thought.
Could be a fun read.