According to an Onslaught update of Apprentice, there are 12 creatures in November 1st Type II that can produce mana, but several can only make it when you sacrifice something. Here's the list:
Birchlore Rangers
BoP
Blood Pet
Fyndhorn Elder
Harvester Druid
Llanowar Elves
Nantuko Elder
Overeager Apprentice
Seton, Krosan Protector
Skirk Prospector
Werebear
Wirewood Elf
Not a very promising list...