Forty years is a long time for a tree to grow, but an even longer time for a memory to take root.

In the spring of 1984, my husband Mark and I were exhausted, terrified, and blissfully happy. We had just brought our daughter, Lily, home from the hospital. The day after we settled in, Mark went out to the backyard with a tiny oak sapling in a plastic black pot. I watched him through the kitchen window as he dug a hole right near the edge of our property, patting the soil down with his bare hands.