On early space habs, those first fruits may be something like some algae and a guinea pig. :-)

Ok, algae isn't likely to be more than an intermediate stage. but it could be *very* symbolic.

Ooo! a "feast" celebrating survival of major damage to life support. Eating algae and rats or guinea pigs or the like in remembrance of what people had to eat while waiting for the new crops and animals to reach harvestable age.

Ceremonies for establishing a new habitat or colony. Bringing in "starter" plants and animals, placed in a special "greenhouse". They wouldn't be the actual "starters", but a symbolic thing. For the nature types, that would be a holy place.

Hmm. some special plants and animals traceable clear back to Earth that are mostly for ceremonial use. Mistletoe? Doves?

And sometimes new ones get added from planets that had compatible planets.