Halfway down the garden, in the middle of the thick yew hedge, a wild plum tree is heavy with fruit, each one hanging like a bauble on a Christmas tree. The tree was never intentionally planted and is probably the result of my habit of throwing plum stones into the garden. The first I knew of it was an arching branch of snow-white blossom that appeared from the hedge one spring. Late each summer, its branches are bent low with chartreuse…