Board Thread:Plants vs. Zombies Heroes/@comment-30553109-20180526160730/@comment-27835295-20180610231109

Also, Potato Mine, Sizzle, Sweet Potato, Vanilla, Bloomerang, Yeti-Lunchbox, Cell-Phone Zombie, Cakesplosion, THE ALMIGHTY, OP DEAD MEME RA ZOMBIE, and Firefighter are now commons.

I would go to the Hero Quests page to check if these are crafted in quests, but it's very old and inconsistent, so I can't be sure what is true.