My dad thinks it may have something to do with the underground railroad for some reason. I live in the Hudson Valley in New York. So some of the letters are hard to make out, and i would have to rip up more white wash to reveal more, but some of the letters were crumbling. Here is the link: Imgur
Can you post another photo or two so the symbols are clearer? Alternately, highlight or draw them since you can see them better in person.
Also, have you spoken with your local historical society? They may be able to both assist in finding out the owners or heritage of the home itself, which could shed quite a bit of light on the subject. Many have extensive maps and records of individual homes, fire insurance maps, parcel maps, etc. I'd venture a guess that they'd be quite interested in it!
There is a brick collecting club focused on the Hudson Valley, whose members specialize in identifying marks on old bricks. It may be worth getting in contact with them over at their website. Now, yours is hand-carved rather than a maker's mark, but if anybody is familiar with it, those folks are likely to be.
