Question
QUESTION: I would like to know how you know the difference between a moon vine and a moons flower.  A friend gave me a hull with stickers on it. I broke it apart and planted the seeds.  Now I don't know which one i have.

ANSWER: Hi Craig,
thanx for your question.  Another name for the moon flower is thornapple.  It sounds like you have a moon flower or thornapple.  Also known as datura (botanical family), jimsonweed, Gabriel's trumpe, angel's trumpet.  A moon vine, is a giant morning glory that blooms at night (Ipomoea alba) and is a shortlived perennial in warmer climates.  It's seeds are found in a cluster of 3 or 4 and look somewhat like corn kernels.  they are found in a berry-like fruit, usually, black or dark brown.  The moon flower (datura/thornapple seeds)does resemble a tomato seed because they are in the same family - Solanum - nightshades.  I hope this helps.
Tom

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QUESTION: someone told me that a moon plant or at least some of them are poisonous to animals as well as humans how do you know if you have one of them

Answer
Hi Craig,
Thanx for the question.  Both datura (moon plant, jimsonweed, thornapple, etc.) and the moon vine (Ipomoa alba) are toxic if ingested.  Usually, when referring to toxicity generally the discussion is around herbivores like pasture animals that will eat anything green and the offending plant may be growing amongst the forage.  I had both plants in the yard and my dog never messed with them.  That doesn't mean a dog wouldn take a spare chomp here and there but I highly doubt it.  There are literally hundreds of poisonous plants growing in your yard.  Here is a partial list from Texas A&M University.  I hope this helps.
Tom

http://plantanswers.tamu.edu/publications/poison/poison.html