Books of Letters

I am compiling a list of books based on letters written between gardeners, like Two Gardeners: A Friendship in Letters. Does anyone know of other books like this?

I know I've seen a few while poking around Amazon - I'll keep my eyes open and post if I see them again.

The 3,000 Mile Garden: An Exchange of Letters Between Two Eccentric Gourmet Gardeners by Leslie Land (ISBN 0140254471)

You may want to look into some of the correspondence of Thomas Jefferson. He was perpetually writing to friends about his gardening and garden experiments to paraphrase, "I am an old man, but I am a young gardener."

I like to read letters about gardening. What a nice idea to make a list of these books!