Well I dont know if I've got an "extensive knowledge" but UFO / alien entities is a subject I've done some research on, thought about a whole lot and have had som experiences with (during dreams and other altered states of consciousness). I tend to think of UFO as a phenomenon in the same category as spirits, faeries, angels, etc - that is, as experiences on the border between human, earthly consciousness and the dreamtime of outer space. I believe that the universe we are part of is a living, consciouss organism and that this cosmic mind can be thought of as a broad spectrum of experience, human mind and alien mind are different wavebands of consciousness. UFO and alien beings (faeries, grey, etc) are how we percieve contact with those other parts of the cosmic mind. Psychedelics / entheogens, lucid dreaming, active imagination, trance states, etc are different methods to open up to such influences.
UFO sometimes get caught on photo / video (even though there are many examples of fraud or airplanes / balloons / etc being mistaken for alien spacecraft). The temple rock ufo is one cool video, I cant judge wether its the real thing or not but it looks promising.
Re calea I dont know more than I've been able to read on the web, but I understand that its quite easy to grow at home. Have you tried it? Did you find it useful?