I'm just spitballing here. You can grow a tree and give it a pulse of electric current to somehow alter the ever slowly growing rings in the middle of the tree (the rings you count on a cut down tree to tell its age) that will give it nano changes that can be sequenced into 1s and 0s (microscopic) then to get the data out; you could blast the tree with a sonar device to pick up the microscopic 1s and 0s to pull out the data. All machines in this example only exist in my imagination.