Safety is a concern even when gardening. If you use chemicals of any kind, fertilizers, and pesticides be sure to thoroughly read the label and follow the instructions. This is one are that is often neglected — much to the peril of the gardener or dire results in the garden, from not following instructions properly.
Here are some websites with garden safety information:
List of Tocic Plants: http://www.plantsciences.ucdavis.edu
Garden Safety with Children: http://www.associatedcontent.com/article/1114319/gardening_safety_with_children_home.
SafeKids: http://www.safekids.co.uk
Cooperative Extension Office: http://www.csrees.usda.gov/Extension/
American Association of Poison Control Centers (24-hour hotline): 1-800-222-1222