This is an excellent mosaic-style pack, I would really like to see it's further development. I'd say if you're worried about the pumpkin, do something completely different; Remember the pumpkin's face doesn't have to be a face, or a pumpkin for that matter.
One thing I would suggest is to have the unlit pumpkin show a void, and when lit, various colored/toned panels are revealed. Could do the same thing with Glowstone/Redstone Lamps?
(If you found this some help, I am glad, if not, I'm happy to have at least tried )
I've already done the pumpkin, pretty happy with it. It has a square with a brownish background. When lit, it shows a torch. I might make the lamp a box with a hole that glows. I'll have a think in the future.
PS. I like the way you describe it as a mosaic. I'll add that to the OP.
Mossy brick, cracked brick, piston top, circle stone....man, some of those don't look anything like the other textures. The stone brick is so clean and crisp, and the moss/cracked varieties almost look scribbled.