Julia passed along this website this morning. It has a list of posinous plants that can cause harm to the pup. Not all of them are life and death, it just states that they may cause a toxic reaction in a pet. "Poisonous plants produce a variety of toxic substances and cause reactions ranging from mild nausea to death." So it turns out we have two of these in the backyard the first is the Sago palm. It sits in a pot in the backyard and is described here as causing "Diarrhea, Liver damage, Vomiting, Increase in water intake, Nervous system depressants, drowsiness, coma, muscle paralysis"This is a picture of the sago palm.

We also have a plant called an Elephant Ear, soemtimes called Angel's Wings. As far as that goes here it says:

Elephant Ear: These plants with leaves up to 4 feet (1+ meter) are related to taro and grow in wet, muddy conditions near streams and rivers. Like the taro plant, they contain invisible calcium oxalate crystals, tiny sharp needles inside the plant cells that irritate the skin. What I did not know is that these plants have a cell mechanism to project the crystals whenever a leaf or stalk is broken. Crushing or chewing the leaves or stems will cause a burning rash where the crystals embed in the skin or mouth. Differernt species had varying amounts of calcium oxalate. Taro leaves must be thoroughly cooked, and elephant ears were only cooked in times of famine.

Above is a picture, I don't think this is the same as the one in the yard but it may be of the same species so he should stay away. That's about enough to worry about for now though. We'll work on moving them so there is never a question or worry about him getting into them. This site also seems to have some good advice on keeping things safe for a pet and generally cutting down on pests in a garden. With all the potted plants around here this is definitely something to stay on top of.