My house was built in 1929.  When I got it the back yard was lawn from picket fence to picket fence.  It is now stuffed with biomass: apple trees, carraganas, roses, raspberries, peonies - the prairie gardener's friend, lilacs, little pieces of lawn for the dogs.   Still, and this is after 30 years of a lot of digging for vegetable patches and for moving things around, one cannot stick a fork in the ground without turning up a marble.   
Not surprisingly, given that playing marbles mostly involves shooting marbles into holes in the ground, many are lost, only to turn up decades later clutched by roots and earthworms.

Of those found in my yard, some are quite old, a couple are clay, most are well worn. When I was little, crystals were really special but now, with my collection of back yard marbles, I quite like the china ones – the ones that look like china rather: white glass with fat slashes of colour. I suppose if one was a marble archaeologist one could date them, but I think the marble playing heyday started to wane by the late 1960s.

I was rubbish at playing marbles, never really got the game.  It was also the new postwar era of marketting toys to children: bolo bats, hula hoops: cheap toys with built in obsolescence.  Marbles, clearly, are indestructible, subversive anti-consumer products. Their only problem was in getting lost.