We had a Quince bush outside the patio door at home when I was little, Mum ever the resourceful type didn't know what it was or if it was edible but saw this nice fruit every year so she made Quince Jam/Jelly, a bit sharp from my memory and I don't think it got made again. And I think it was red not green.
Martin
Ours are like furry pears, yellow in colour, and as hard as stone. Takes some strength and determination to cut through even one!!! No wonder they're not popular.