Thank you for your email. I am posting more details on Trulia as it might help also other folks.
Owner.com is an example of a good FSBO site where you can search based on zipcode and specific distance from that zipcode. I searched for 02465 and within 15 miles. It returned 138 FSBOs. You can also get an email alert with new FSBO fitting your search.
This is the result:
There are many FSBOs websites you can use to get this info but not on Trulia.