music identification - What is the song playing in The walking dead S2e5 when daryl pulls the arrow out and in s3e10 when daryl and merle help the mexicans?

What you are talking about is not a song, but rather a musical cue. See, the Walking Dead is scored by one Bear McCreary. The only possible name that I could find for it comes from this forum post which refers to it as Daryls theme/Dream tones. Luckily, he wrote a whole blog post talking about what he was hoping to accomplish and embedded a nice video showing how he came up with the sounds you heard.

However, that particular piece of music hasn't been rerecorded anywhere I could find, so I can't link you to a place to buy it. Of course, it's not the only place he uses those tribal style drums in his music, so if you cruise through some more of his work, you will probably find some stuff that speaks to you just as much!