Romaine, Zucchini, Cucumber, Asparagus among others, but those are what I use. Anything will seeds will drive a Melanura/Synspilum Koo-koo for Cocoa Puffs
My Syn/Melanura Meatloaf RIP ate everything. He really didn't make much of a mess either as very few food items actually touched the water before he did his fat kid thing. I made frozen food along with fresh stuff. I just mash or dice add boiling water and freeze.