@OkiF-- I've wanted to do that too [a flat dish of dirt w/ seedlings growing] for our dove to have access to. But concerned w/ the dirt issue.
Thought maybe a chia head w/ grass growing would work--- what do you think?
I like your idea of the chia seed. As I said I am still thinking about it and trying to sort out the issues.
It seems that in Namibia roseicollis lovebirds ingest a significant amount of soil (and to a lesser degree, cattle and horse poop), so in a natural environment eating a bit of soil should not be a problem (even potentially bringing in good minerals, etc). However, in a cage we don't have the soil associated fauna that help keeping things (i.e. bacteria) in check. So while in theory bird poop would feed the seedlings that will in turn serve as playground/food for your birds may turn in reality to a nasty goo. In this idea, the chia seed head sound interesting. I tried growing the seeds on some wet kitchen paper, while promising at the beginning, it became rapidly very "alive" (but not only with the seedlings).
We had a Dracaena massangeana that the birds did not mind too much except for a few nibbles, but before Inkochan died quite abruptly he kept going at it and chewing on the leaves. This plant is supposed to be safe and it may be that if he had some digestive issues due to metal poisoning (metal poisoning is our most likely hypothesis, but we did not perform a necropsy) he may have looked for the plant to help somehow. We will never know, but we decided to move the plant out of reach of the birds as it is not worth the risk.
Palms are a safe group of plants with rather hard leaves, some small ones like Phoenix may be something to consider? Areca palms (Dypsis lutescens) are also common indoor plants (our outdoor depending where you are). I am now using the wood of some old areca palms for perch, swings and other enrichment, it actually a pretty nice wood.
But please take my experiences with a big grain of salt, I am not an experienced bird parent, just learning as much as I can...
P.S. If of interest, you can look for the Namibia paper online, it is from Ndithia and Perrin (2006) "Diet and foraging behaviour of the Rosy-faced Lovebird Agapornis roseicollis in Namibia" and was published in "Ostrich: Journal of African Ornithology".