Everyone who grows tomatoes and related plants should heed the warning posted by @seankyleb ; in addition to the nasty spines, the poisonous aspect, the invasive nature and the harm it does to the local plant life, the plant is also a host and/or alternate host in the spread of several fungus or virus diseases that cause damage to potato and tomato crops.

Looks similar to the young growth of Solanum capsicoides, Devil's Apple. A noxious invasive weed.

http://www.hear.org/pier/image...

http://www.discoverlife.org/mp...

http://florida.plantatlas.usf....

My guess would be Solanum viarum (Tropical Soda Apple) which is a non-native invasive here in Florida:

http://plants.ifas.ufl.edu/ima...

http://plants.ifas.ufl.edu/par...

http://www.fs.fed.us/database/...

Tropical Soda Apple (Solanum viarum)