Yes there are shelf life's to seeds. The life will depend upon several factors. Type of seed, how seed is stored, temp in which the seed is stored, humidity in which the seed is stored. Generally speaking however the older the seed is the lest likely it will germinate. If you have seed packs, you may find a use by date on the package.
Different seeds definitely have different shelf lifes, as Woodbridge says. For a pretty comprehensive list, see this from Colorado State University Extension:
@Brandi Hegerty if you are wondering if they will germinate, you could always take a few and place them in a glass lined with paper towel and with some water. Place a few seeds between the glass and paper towel - much like they do in elementary school to teach kids how plants grow. If it germinates then you can try it in the garden, if not add it to the bird feeder. I can never remember when I purchased the seed, I should put a date on the package. @Woodbridge Environmental Tiptophouse.com and @Douglas Hunt have provided more professional advice to follow, so I would check the website. Thanks for posting :)