The Smithfield Preston Foundation Papers consist of 200 letters written almost exclusively by two generations of members of the Preston family of southwest Virginia, Kentucky, and South Carolina, to James and Sarah Preston McDowell of Rockbridge County, Virginia. The collection also includes a will of William Campbell Preston, an obituary of John Smith Preston and his photograph, and a circular asking for funds for a memorial in honor of John Smith Preston.

Many of the correspondents are the children and grandchildren of William (1729-83) and Susanna Smith (1740-1825) Preston, settlers of Botetourt and then Montgomery County, Virginia. The letters were written by Sarah Preston McDowell's brothers and sisters, and their spouses. Other letters were written by the children of her brothers Francis Preston and James Patton Preston. Most of the letters are addressed to Sarah Preston McDowell and James McDowell or their son James McDowell and his wife Susanna Smith Preston McDowell.