Lyric discussion by aicseason 

Cover art for Sunshine lyrics by Alice in Chains

I say its pretty much entirely about Jerry's mother. "mother please, come for me"

"dude (his father) aint here any more", parents divorvced

"Is my soul entier?" missing part of his soul - mother died few years befor this song was created

Sunshine his last connection to all that is good telling his lovely dog he just dosent care any more as hes lost everything that mattered.

Could be really wrong but just as i see it.