Hatching duck eggs

I've got 5 duck eggs in my incubator. 3 of them are a pretty blue-green color and two of them are white and larger than the other 3. Next Wednesday will be day 28 since they've been incubating. When I candled them this morning, it's obvious at this point which ones are more along than the others. The green ones look like they are closer to hatching than the white ones. From what I've read, Muscovy ducks take an extra week to incubate and since there were Muscovys at the pond where I found these eggs, its seems obvious to me that the white eggs are the Muscovys. Still scratching my head over the green ones though. The pond was at an RV park and the owner had Muscovys and Pekings. But I also saw what appeared to be a Mallard as well. I wish I would have paid more attention to what breeds were in the area instead of being like a kid at an Easter Egg hunt! The eggs were scattered everywhere. No obvious nest.
Since the 3 green eggs are closer to hatching, I'm thinking about putting them under one of my broody hens in a few days so she can hatch them for me. I'm wondering what possible breed could these green eggs come from?