I've said this many times, most children spirits are not children. Nature spirits tend to look like children because they appear youthful and tend to be between 3-4 feet in height. Their eyes give you an indication of their nature. As the old saying goes, the eyes are the windows to the soul. Since they were green, I would assume he is benevolent. The blonde hair reminds me of the description I've read of light elves recently, although I've never personally worked with them and can't tell you first hand.
But being good doesn't necessarily mean innocent and just because they look like children doesn't make them naive or unintelligent. Most nature spirits are mischievious and very smart. This one obviously wanted to let you know he is around and wants to be your friend. Make sure if you do go ahead with contacting him and making friends, you have a good sense of humor and don't scold him like a child. Remember he is much older than you and deserves respect no matter what. He may do things just for entertainment that is harmless but annoying if not laughed off. I personally try to avoid nature spirits, as they can be hard to handle. The little ones tend to have a five year olds personality with the wisdom of a hundreds of years.
My daughter attracts the tiny ones, I was always skeptical about their existence until she was born. But I can't deny it anymore. It didn't suprise me when she instantly became obsessed with the image of fairies from the age of two on, even before she saw Tinkerbell or Winx. As an infant, she would giggle loudly and randomly when I would turn away, and when I looked back, I wouldn't see a darn thing! Enough to make you feel like your going crazy. Sometimes I'll fall asleep at night and hear the sound of a child giggling. Its become the norm around here. My husband and I have just accepted it. Lol