"last discovered" is a grammatically correct phrase and can be used in written English.
It typically refers to something that was recently found or learned and is being referenced as the most recent discovery. Example: "The last discovered species of dinosaur was the feathered Sinornithosaurus, found in China in 1999."
It is 15 years since we last discovered a bird's-nest orchid.
Farmers have at last discovered they can store hay and sell it for a higher price during the rains.
Bresson's detractors sneered that he'd at last discovered his ideal protagonist, and in a sense they weren't wrong.
More than 20 years had passed since researchers last discovered a new collection of chemically related superconducting materials the ceramic copper-oxide superconductors.
Ill and exhausted by his restless existence, he at last discovered the literary form that ideally fitted his lively and disillusioned temper: he wrote his first contes (stories).
Even the most hastily constructed salad or dish of pasta is transformed by a whiff of basil, and gardeners have at last discovered that in the right conditions, it's not difficult to grow.
We shall at last discover the secret of making surplus value.
In the tech heartland, this is the ultimate compliment.You may joke that America is at last discovering Europe.
Coupled with her sly, stylized performance in "Moulin Rouge," this role suggests that she is at last discovering her range as an actress.
There's a nice moment when Jack, at long last, discovers her dark arts — the arts of Isabel, that is, rather than Samantha.
But there is more passion in this nostalgia than a wistful backward look: it reads to me like someone at last discovering ideals which offer something more substantial than the greed and terror which characterised his own world.
