I am a big fan of the privet cassia (Cassia ligustrina, a.k.a. Senna ligustrina). It is a native, and is rather elegant IMO - the form reminds me of bamboo or ginger. I think I remember reading somewhere that it is not very good at nodulating and fixing nitrogen, but that it is still beneficial when intercropping with other food plants. Undoubtedly does better down south than in Jax, up here it is a die-back
perennial at best.