I found this website some time ago, and thought that I should share it...
http://www.mreinfo.com/
It has a pretty good amount on MREs and the equivilents of other several other national militaries. It also has reviews of how these prepared meals taste... This might help set the stage for how things taste and allow the PCs to get a better feel of just what their character is eating to survive (and make them dream of 'mom's' home cooking)!