This happened 5 years ago when my son, John, was 5 years old.
He and I were at the local cemetery putting flowers on my first sons grave. He had died shortly after birth from a heart defect. John had been there several times with me and he knew why we were there. As I was kneeling on the ground clearing out the old flowers and putting the new ones down, John was chattering away behind me like all kids do. John asked me if there was a party there today and I told him no, thinking he was asking if there was going to be a funeral procession. We were alone in the cemetery. John then asked me "what are all the people here for then?" I looked around, there was nobody there. He couldn't have been mistaking the headstones for people because this cemetery has all the in ground stones that are level with the ground, there are no monuments sticking up anywhere there. I asked him if he meant the dead people buried here and he said "no, the ones all standing around smiling at me". That's when I decided it was time to go. I grabbed Johns hand and we headed for the van about 100 feet away. All this time, John is looking back over his shoulder and waving at somebody I didn't see.
We left there and he didn't say anything more about it and I didn't ask, but the next time we drove by there, he smiled and waved again. I asked him who he was waving to, and he said "the pretty lady in the blue dress" Of course, when I looked there was nobody there.
John is not the type of kid to have imaginary friends. He never has, and he never says things like this at home, so I truly believe he saw some people there that I couldn't see.
Once, I asked John about who he saw there and he told me "just some nice people that smile a lot and like to watch people plant flowers" then he went on to tell me about his new Pokemon cards he just got.
Can kids see what we can't because we refuse to believe things exist such as ghosts? I know that now, I believe they exist, and I also believe they are not something to be afraid of.