I live in suburban central New Jersey (USA). Just a block from my
house, there's a footbridge which spans a ravine. Fifty years ago
there were railroad tracks at the bottom of this ravine, but now
there's just a muddy rut; the sides of the ravine have little on them
but sparse weeds.

Earlier today I was walking this footbridge, and it occurred to me that
I could make a beautiful gift to my community by seeding the ravine
soil with some sort of colorful flower. I imagine walking over the
bridge in midsummer and having the gentle scent of flowers envelop me.
Meanwhile, a vibrant carpet unfolding on the ravine walls beneath.

I know next to nothing about flowers though. What would be a hardy,
colorful, gently scented, perennial flower that grows well in central
NJ soil, especially a relatively steep slope? (If nothing fits all
these specifics, feel free to match just a couple of them!)

Thanks so much for your help!
John in NJ