Champion conkers are rated by the number of opponents they have vanquished, so there's a process of selection improving the champions.
It is generally considered unsporting to prepare them in certain devious ways, such as baking them for 800 years in the family ovens (to quote the Molesworth books ahem).
I regret that I have only actually seen one conker match in the last twenty years - in a pub. I don't know whether children routinely play it in schools still (and I have the same ignorance of marbles, hopscotch etc. in these days of hand-held electronics), or whether it's now relegated to the lumber room of our history along with morris dancing, trotted out only for the show.
I don't see children collecting them. I pick up horse chestnuts because they're exquisitely beautiful, and I wouldn't dare risk harm to my favourites.
