According to Wookiepedia, Obi wan was born in a planet called Stewjon (named after comedian Jon Stewart). But the movies don't give us much information about Obi wan's origins, and childhood. We are introduced to him in Episode I just as Qui Gon's padawan. I think the prequels should have given more details about his origin, because Obi is one of the main characters of the saga. So, there are any novel, or comic or something else in EU explaining more Obi wan's family and life in "Stewjon" and how he was found and became a Jedi?
Given that Jedi are adopted into the order very young (4 was considered extremely old in EU media covering this) - that might be why nobody went into detail on the pre-Youngling Obi-Wan.
Why would you assume he was abandoned? More likely he was simply identified as a Force-sensitive as an infant and willingly given up to the Jedi Order by his parents. From what we see and are told in canon sources, that seems to be the norm.
I don't see the point. The original films gave very little or hardly any background information on Han, Leia or Lando. And I agree with The_Phantom_Calamari about how Obi-Wan ended up with the Jedi Order.
Obi-Wan seems to have an especially strong bond with Yoda, and I wanted something other than the norm.
I see their bond (if there is any) more as a result of them being the only two Jedi left (speaking just from the movies).
Earlier EU sources say Obi-Wan was from Coruscant, which I still take over the silly 'Stewjon' nonsense. I think it was clear that Lucas was making a joke, but the people who take Lucas' word as gospel were a bit too literal with that.
Of course he was making a joke. No one, including Leland Chee, ever thought otherwise. Its canonization as Obi-Wan's actual homeworld was meant to troll people who take all this stuff way too seriously.
Even in the old EU Obi-Wan and Yoda's origins seem to be kept intentionally sketchy. I hope the reboot keeps it that way. Unless they manage to pull off an awesome Obi-Wan origin film. Yoda/Yaddle species and homeworld however, should always be kept a mystery imo.
If you want some young Obi Wan based EU read the Jedi Apprentice series. Not sure if it would even be somewhat considered canon, and it's definitely for young readers (it's scholastic, I believe) but it covers a lot of Obi Wan's training. There's also the comic book "Jedi." As for pre-Jedi, there aren't really any roots and there doesn't need to be. Imagine if we got a backstory for every main character. We don't need Obi Wan's, or Yoda's, or Qui Gon's. The saga is about Anakin/ The Skywalkers. That's all that's important.
I have this weird headcanon that he's from a royal family of some Core World where his mother is Queen. And I always picture her as Julie Andrews!
It would be kinda cool to explore/find out about Obi-Wan's origins. Who knows, maybe they will address this in his spin-off films.