Well it's rare to have a couple of Hesse fans in the room! I thought you might find this a treat.
My father carried on a lengthy correspondence with Hesse, and I have an accordion file full of letters, signed photos, manuscripts and even some unpublished poetry. The photo shows a small sample. I have been in touch with various archives who are dead keen to have this material, but just haven't been able to decide where it should go in the end.