I got all three samples today and some of the things sent are quite interesting.
Lafeber sent four kinds of Nutri-Berries, two kinds of Avi-Cakes, and two sizes of their daily diet pellet. Pigpen and No Name got their pellets mixed in with their seeds and I'm pretty sure they've eaten some since they're a natural color. Cheney Bird got a seperate dish and didn't seem too impressed, but he did nibble the Avi-Cake.
Harrison's sent three sample size bags, two of the fine and one of the super fine. I'll try these tomorrow with them, but again they're natural colored, so they may not be a problem.
Oven Fresh Baked sent a decent sized sample bag of their medium pellets. At first glance, they're kind of weird looking. I kind of thought they looked burnt. When I opened the package, I smelled cinnamon right away. I'm not sure if they put cinnamon in them since I didn't see in on their ingredient list, but Cheney Bird did seem to nibble on them and enjoy them.
EDIT: It appears that I lied. I mixed the pellets in with the seed and hoped to trick them into eating the pellets that way. It appears that they are digging around the pellets for the seeds. I put Avi-Cakes and a Nutri-Berry in there for them as well, and the Avi-Cake was tossed to the cage bottom.
I don't think I'm going to change their food dish tomorrow and let them finish the seed and be stuck with the pellets. I'm hoping they realize the pellets are food and will eat them. Otherwise, I'm out $49 because I thought they ate them and ordered the ZuPreem 20lb bag of pellets and 10lbs of seed blend.

"Mockingbirds don't do one thing but make music for us to enjoy. They don't do one thing but sing their hearts out for us. That's why it's a sin to kill a mockingbird."
- Harper Lee, To Kill a Mockingbird