Oh, okkkkkkkkkk! I came on to the Gardening forum looking for the answer to this question.
I'm going to take Breezycooking and Charlie's advice and plant some of my 3 -year-old seeds instead of tossing them.
In case it makes a difference what type of seed, they are Kentucky Wonder pole beans, yellow bush beans, radishes and sunflowers.
They have been kept in a dry spot in a closet, the packages have not been taped shut, just folded over, tucked in pockets of my gardening bag.
Hope you guys are right!