I’m not sure what your budget is, and I know that a lot of the better-advertised NJ venues can get *very* pricy per guest. We’re getting married in NJ, too, and our caterer, Falco’s Catering, has very reasonably priced menus (for the area). Barbecue menus may be the most affordable option; they range from about $15-40 pp, but don’t include wedding cake or extras (the bbq menus aren’t designed to be wedding menus, but the people there are very nice & flexible, and could probably work out a reasonable add-on plan for you on that score). Wedding menus range from $68 pp for a buffet to $80 pp for the Grand Plated Wedding, and all of their prices *include* tax and service charge (so it’s like getting a 17-25% discount vs. other places that have a mandatory service charge *on top of* their stated prices). Their prices do *not* include liquor, but they’ll order whatever you need & return any unused liquor afterward, so you only pay for what you order & use. They do off-premise catering, including at Bayonet Farm: http://www.falcoscatering.com/bayonet_farm_nj.html and a few other outdoor locations: http://www.falcoscatering.com/pine_grove_caterer.html.
There’s also Perona Farms in northern NJ, which has a barn setting and an orchard setting available, among others. Their website is (http://www.peronafarms.com/wedding/) — it doesn’t list any prices, which always worries me with fancier-looking venues, and they definitely look to be on the upscale side, but it couldn’t hurt to inquire.
DRJ Catering does barbecue, pig roast, and other menus (including seafood, action stations & gourmet cuisine) off-premise, so you might look into them if you wanted to use a park / state park or historical site. Their website doesn’t give prices, but a friend used them for her backyard post-wedding pig roast, and swears they’re affordable. Their website is: http://www.drjcatering.com/menus.html.
(Note: if you do decide to go with a park, state park or historical site, make sure you check into whether they allow alcohol & what permits are required for special events. I’ve looked into several parks, and most of the fees are pretty inexpensive, but sometimes extra permits or fees apply if you have over a certain number of guests, or if you’re serving any form of alcohol, etc. A good off-premise caterer should be able to tell you what locations they’ve had success in working with.)
Flanders Valley has a gorgeous country setting bordered by hills and a horse farm. Their setting may be a little fancier / less rustic, depending on your taste. Their menus range from $70-90 pp for a plated meal (they also have a buffet menu, but don’t list its price), and their website is http://www.flandersvalleyweddings.com/menu.html.
Lastly, The Inn at Fernbrook Farms has a wide range of formality levels and a great commitment to farm-fresh foods with an emphasis on sustainability. The grounds are beautiful, too! I’m not sure what your wedding menu would cost with them, since so much depends on what you want — they’re big on customization, but if their menus are out of your price range, I *believe* they allow you to bring in an outside caterer. Their website is: http://www.innatfernbrookfarms.com/weddings/
I hope the info helps!