I'm actually debating both wheat-like grains and sheep.

They're both great if your goal is to have a large surplus of something that's easily commodified - in other words, if you're empire-building - but in terms of trying to build a small, sustainable community (especially in a climate with a long growing season, where having winter stores isn't vital) they have some pretty significant downsides in terms of labor and environmental costs, compared to using things like root vegetables or beans as staple starches.

And you don't need bread for penicillin! I think the strain that eventually worked best in the end was actually from a tomato or something like that. (they will be growing their bacterial medicinals in culture media, I suspect.)