johnbob.net has four versions:

A song Dad used to sing...
(a BIG thank you to Cat Yronwode for sending me the words. I only ever heard Dad sing about 1 or 2 verses. Cat says she's still missing a verse about "that's our recommendation". Hopefully someone else can come up with it.)

The Great American Bum
Harry McClintock

Come, all you jolly jokers, and listen while i hum,
A story I'll relate to you of the Great American Bum
From the east and west and north and south Like a swarm of bees they come
They sleep in the dirt and wear a shirt That's dirty and full of scum

Oh, it's early in the morning 'ere the dew is off the ground
The bum arises from his shack and gazes all around
From the boxcars and the haystacks, He gazes everywhere
He never turns back upon his track Until he gets a square (a square meal, that means)

  (this next part is spoken dialogue, with a woman who has a strong "Oirish" accent)

[knock! knock! knock!]
—Good mornin, Mum!
—Good morning, Bum!
—Mum, could you spare a loaf of bread?
—Go away, Bum, the baker is dead.
—But, Mum, i've been walking all morning!
—Well, you can keep right on walking!
—Honestly, Mum, wouldn't you have a bite to eat in the house?
—Aye, that i would, Bum -- and a six-foot Irishman comin' home at five o'clock to eat it! On your way, now!
—Goodbye, then, Mum.
—Goodbye, Bum

Oh, sleeping in the pokey, fogey-ogey-ogey
Smoking pipes and stogies, ha-ree, ha-rah, ha-rum
For we are three bums, three jolly old bums. We live like royal Turks
We have good luck in bumming our chuck To heck with the man who works!

Here's some more verses from Tolbert Eldon Ashbrook
(not sure where they fit in the song but at least we got'em)

Oh it's early in the morning, Ere the dew had left the ground,
The bum arises to his feet, Begins to search around,
From the hammock to the mansion, He searches everywhere,
Never lights upon a strike, (meaning a lucky strike cigarette) Until he stikes a square,

Bum the streets in Gad, boys...
Leathery leathery dad, boys...
What a drunk we had, boys...
Leathery leathery day....

Here's a similar version emailed to me from Harold Recknagle
He learned the song, from an itinerant logger, when he was a lad living up on Lake Chelan, in Washington State in 1948:

The Great American Bum Come all ye jolly jokers and listen while I hum The story I'll relate to you, the great American Bum From East to West from North and South Like swarms of bees they come Sleep in the dirt and wear a shirt, filthy and full of crumbs It's early in the morning, the dew is on the ground The bum arises from his nest and gazes all around From boxcar to the haystack, he gazes everywhere He never turns back upon his track until he gets a square I've topped the spruce, I've worked the sluice, I've taken a turn at the plow I've dug for gold in rain and cold And worked on a river scow I've picked the clam, I've packed the clam I've packed the elusive prune But my troubles pale when I hit the trail Packing my own balloon Oh lady would you be kind enough to gimme a bite to eat A piece of pie and custard and a ten foot slice of meat A piece of pie and custard to tickle me appetite For lady, I'm so hungry, I don't know where to sleep tonight Oh it's sleepin' in the station, tra la la la la lation That's our recommedation, harrah haroo harum We are three bums, three jolly bums, we live like royal Turks We have good luck abummin' our chuck. God bless the man that works Oh I met a man the other day, I'd never met before He asked me if I wanted a job shovlin' iron ore I asked him what the wages were, he said ten cents a ton I said ol' fellow, go chase yourself, I'd sooner be on the bum Oh it's sleepin' in the oggies, hi oggy oggy oggies Smokin' snipes and stogies, harrah haroo harum We are three bums, three jolly bums, we live like royal Turks We have good luck abummin' our chuck God bless the man that works Here's a similar version emailed to me from H. Carl Klindt as he remembers them >The Great American Bum It's early in the morning The dew's still on ground The bum crawls out from his nest And gazes all around From the boxcar and the haystack He gazes everywhere He'll never turn back upon his track Untill he gets a square I was sleeping in the shade To pass the time away A man woke me up and asked me To help him get in some hay He said his land was rolling I said now if that is true Roll it here to this shady spot And I'll see what I can do Once I met John Farmer He stopped me on my way He said he was digging potatoes And they had to be dug today Now I can't dig any potatoes 'Cause I'm getting fat Go hire the man that planted them He knows where they are at (dialogue) "Good mornin' mum" "Good morning bum" " I was just passing by" "Why did you stop" "I haven'nt eaten yet today" "SO" "I have'nt seen my wife for many years "SO" "Well mum I have a button here" "Would you sew a shirt on it for me" "WERE IS MY BROOM GET OUT HERE ON YOUR WAY" "Goodby mum" "Good bum" My clothes are getting ragged My shoes are getting thin But what do I care I've got to wear I'm on the bum again The weathers getting chilly Soon all will be froze I've got to go to a sunny state Where the weathers fit for clothes