http://thepoetryofsight.blogspot.hk/2014/03/collections-poster-travis-tjelmeland.htmlFlower shop owner, quoted in Abraham Pais, Einstein Lived Here. NY: Oxford University Press, 1994, p. 26—
When he [albert einstein] would pay his bill [at a flower shop in princeton nj] with his check I would save them. I thought the autograph was worth more than the check. When I had accumulated quite a few, Dr. Einstein telephoned and asked if I would cash the checks, so he could balance his check book.
He also offered to provide us with as many of his autographs as I wished.