You wrote that your first contact with this neighbor happened after your husband was mowing outside of your property line in an area the neighbor uses to access his field. Your husbands good intentions may have been misunderstood as an intent to represent the mowed property as yours. That narrow strip of land may have been a source of contention between the prior owners of your property and the neighbor. Especially, if your property was neatly mowed and that strip was neglected. Is there a fence separating the properties? My suggestion is for you and your husband to pay them a visit with a platter of cookies and a handshake. Then ask them to express any concerns they may have. Heck, he may just want to fish in your pond. Good luck.
