It's a song called Canada Blues, no not really, I'm only joking.
It's Let It Grow by Eric Clapton transposed a full step lower.
That's the first half of the verse which is repeated and then finishes on a couple of bars of A.
The chorus includes A, Amaj7, D, G, and finishes on E7 before going back to the next verse, so I suppose that's in the key of D.
The C I play in the verse should be Am/G but I think the C sounds better. I just like to know what key I'm playing a song in and this one has always perplexed me.