This, for example, is Ilex Verticillata, Winterberry holly. Most members of the holly family have poisonous berries. It is unclear whether these berries are poisonous, or just inedible to humans. The wildlife loves them, however.
If you are close enough to get a good look at these berries, you're already too close.
This is Toxicodendron vernix, otherwise known as poison sumac. The birds will enjoy these berries late in the winter, when other food sources have been depleted.
These are the berries of jack-in-the-pulpit, Arisaema triphyllum. I have read that when chewed, a chemical they contain will cause your mouth to immediately feel like it is full of needles. These are poisonous to humans and livestock.
These are the flowers and unripe berries of pokeweed, Phytolacca americana, a perennial herb, and it is a classic example of a common, poisonous berry that you want to keep out of the hands of toddlers. The entire plant is poisonous. But like jack-in-the-pulpit, parts of the plant are edible if prepared properly.
Plants that are safe to eat only after some specific preparation tend to have interesting stories behind them. Pokeweed greens, for instance, were commonly eaten by the poor in the Southern United States because it is one of the first edibles to grow early in the Spring. After a winter of eating nothing but beans, cornbread, and bacon, I would eat this plant with enthusiasm, too.
Pokeweed was actually sold canned up until about a decade ago. The last company to carry it discontinued the product not because there weren't people eating it, but because they were having trouble finding workers willing to harvest it. Aparently they were hiring people to collect this plant from the wild, rather than cultivating the stuff.
[Update: they taste awful. But perhaps they weren't yet ripe.]
This dragonfly was clinging to the dogwood berries, too cold to fly away from my nosy camera.
Lastly, this is Vaccinium corymbosum, northern highbrush blueberry. They grow in our wetland but have only produced a few berries this summer. On Frye Island, Maine, we ate our way along the road from similar blueberry bushes.