Redbud? Beautiful small pink flowers early in the spring, then a leafy umbrella shape through spring and fall. I'm in Essex Co. and have one in a shady corner and it thrives.

Pic at the link. Not sure how big they get.

Here is a link that might be useful: {{gwi:1062489}}

Redbud (cercis canadensis) was the first tree that came to my mind, too. Lovely color in the spring, shade in the summer. It is native to this region and, according to the USDA, is endangered in NJ. They commonly reach 20-30 feet in height, though mine looks like it's trying to exceed that. It's really pretty trouble-free; we've had no problems with pests or diseases. Below is a link with additional information.

There are lots of other trees that will suit your needs, but I'm drawing a blank just now (bedtime) ... just please stay away from the Callery pears - in addition to the problem of their weak branches, they've become invasive, crowding out native species.

Here is a link that might be useful: Redbud (cercis canadensis)

Thanks any more suggestions are welcome!!!