This is an old jug-band song, recorded by the Memphis Jug Band among others. It was played by the Dead their early days in 1966 but then dropped out of favor.
(1) the original Memphis Jug Band version is "I want you to love me mama like my easy rider done", which makes better sense. But Jerry always seems to have sung "I wanna love you mama ..." And on some versions he sings "I wanna love you rider ..."
(2) again, the original Memphis Jug Band version is "If you don't believe I love you, look what a fool I've been", and similarly for the next line. Jerry often only got part of these lines out, singing "Believe I'm sinking, what a fool I've been" for example on some live versions.
(3) this verse does not appear in the Memphis Jug Band version. I'm not sure where Jerry got it from.
Put your arms around me like a circle round the sun
I wanna love you moma like my easy rider done (note 1)
You don't believe I love you, look what a fool I've been (note 2)
You don't believe I'm sinking, look what a hole I'm in
Stealin', stealin', pretty moma don't you tell on me
I'm stealin' back to my same old used to be
The woman I love she's just my height and size
A married girl, come to see me some time
Well I'm going up North, gonna see my girl (note 3)
Sweetest thing in the whole wide world
Stealin', stealin', pretty moma don't you tell on me
I'm stealin' back to my same old used to be