Here's a list to keep you going which I had posted to a larger thread a couple of years ago.

PENTATONIC SONG BOOK (VOLUME 1)
Brian Brocklehurst

Birds' courting song
Cindy
Git along, little dogies
Hoosen Johnny
Mister Frog's wedding
Night herding song
Old brass wagon
Old Dan Tucker
Old lady sittin' in the dining room
Old Texas
On a long summer day
Poor wayfaring stranger
Sailing at high tide
Sourwood Mountain
The Lone star trail
The mocking bird song
The swapping song
Turn the glasses over
By the clear running fountain
(A la claire fontaine)
Canaday-i-o
Keep the ball a-rolling
(En roulant ma boule)
Land of the silver birch
The Derby ram
With care I tend my rosebush
(A ma main droit j'ai un rosier)
The shepherdess
(Il etait un bergere)
My bonny cuckoo
Deep river
De gospel train
Didn't my Lord deliver Daniel? Ezekiel saw de wheel
Go to sleepy
I got a robe
I know de Lord's laid his hands on me
Little David
Liza Jane
Nobody knows the trouble I've seen
One more river
Steal away
Swing low, sweet chariot
Who's dat yonder?
Auld lang syne
Glenlogie
Leezie Lindsay
Row weel, my boatie, row weel
The auld hoose
The border widow's lament
The standard on the braes o' mar
Wha wadna fight for Charlie?
Ye banks and braes
Cap Cod chanty
Johnny come down to Hilo
Leave her Johnny
Tom's gone to Hilo
At evening
Duck dance
Indian game song
Chimes at night
Fengyang drum
Down the course of years
Lotus blossoms
Sore is my heart
Song of the Gurkha boys
Japanese lullaby
Ahrirang
Blue-bells
Round: Derry ding ding dason
Round: Lady, come down and see
VOLUME TWO

Alister MacAlpine's lament
All night, all day
Buck-eyed Jim
Buffalo boy
California
Ducks in the millpond
Every time I feel the spirit
Fiddle-de-de
Go tell it on the mountain
Goodbye, Old Paint
Hanging Johnny
Hullabaloo Balay
I believe this is Jesus
I want to be ready
It rains and it hails
It's me O Lord
Jennie Jenkins
Jim along Josie
John Henry
King Herod and the cock
Love's ritornella
Lullaby
Mary had a baby
Mister Rabbit
Night doth on the river fall
O bury me not on the lone prairie
O by and by
O Willie's gone to Melville Castle
One morning in May
Perry merry dictum dominee
Poor old maid
Sacramento
Skye Boat Song
Soldier, soldier
Some love coffee
The barnyard song
The cherry tree carol
The little pig
The miller
The old gray mare
The penniless wooer
The poor and the rich
The real old mountain dew
The returned sailor
The riddle song
The Sally Buck
The young man who wouldn't hoe corn
There was a jolly miller
There was a May lived in yon glen
There's a little wheel
Way low down
Where O where is old Elijah?
Who killed Cock Robin?
Yonder mountain