Silloans Farm is one of two farms with internal boundary stones, the other is Headshope Farm. A map of about 1850 shows around 30 stones of which 26 were found by archaeologists doing fieldwork here in the 1970s. Various initials are carved on the stones as well as a cross symbol. Many of the carvings are on adjacent sides and not on opposing sides. Some of the initials include 'D' for Davison or Davidson, and 'R' for Richardson. Such boundary stones appear to be quite rare and may show that the infield and outfield system of farming was still used here in post-medieval times.