I have planted some very old Chaenomeles seeds (probably 3-4 years) harvested from quinces a friend gave us in Lewisham. It is some form of flowering quince but I am not sure what species, let alone cultivar!
The polytunnel is often hitting the requisite 15ºC so I have soaked the seeds and pushed them into the surface of a container (made from a plastic milk carton – I have cut it so as to give an integral translucent lid, which can be removed later). I am not very hopeful of germination but, if it works, it will be a bonus!
There is plenty more old stuff in my stash to work through – one of my aims this year is to clear the decks so I will be trying a lot more seeds over the next few months on the chance that a few of them will make it through.