Ask Mr. Smarty Plants

While we appreciate your comments, we are not a forum, but are set up to answer questions and recommend native plants to gardeners. We did look into this a little, and found there are 16 members of the genus Lathyrus, with several variations of the common name "sweet pea." All are members of the Fabiaceae, or pea, family. Seven of these are native to Washington and the one we chose as an example is Lathyrus palustris (Marsh pea).

These comments are on the webpage you will reach by following the plant link:

"Use Food: EDIBLE PARTS: Peas and very young pods. Collect young pods in early summer and peas slightly later. Do not wash with detergent or sanitizer, only water. (Poisonous Plants of N.C.)
Warning: POISONOUS PARTS: Seeds. Toxic if ingested in large quantities. Symptoms include Lathyrism: paralysis, slow and weak pulse, shallow breathing, convulsions. Toxic Principle: Amine, phenol, and glycoside. (Poisonous Plants of N.C.)"

This does not mention the flowers, but if you removed them from the plant and ate them before the seeds developed, there is no reason for them to be poisonous. Frankly, since childen are smaller and more susceptible to substances, we would not offer them to a child. And, if the gentleman you mentioned cooked up a large batch of the more mature seed pods and/or seeds, he very well could have suffered ill effects.