Hang on to them. Chances are they will still work so you can use them in an emergency.
Make sure you keep at least 3 that are not expired.

Actually, I believe posession of expired flares on a vessel is an offense. Regardless, of whether you have 3 good ones or not.

aim them at sailboats.

Mark, no boat was in the pasture but lots of nice dry grass. Honey was NOT amused!

The Stryker is fantastic! Rides like a limo! I had to buy a new truck to pull it though! Got me a 4wd dually Dodge...

I asked the local CG guys during an inspection and they told me they wouldn't take them, didn't want them. I will try the fire dept.

You can use them to light your smokes!

I like to wrap them in duct tape and go to the bank..................................

Or tape a buncha wires to em and put them in your carry-on bags at the airport.
The TSA will dispose of them for you.

You can keep expired flares on the boat as extras with no problem. In fact the CG auxillary guys thought it was fine. I did give some of mine to them for practice, they were happy to get them.

I chuck them in the truck of the car or back seat of the truck. If anybody ever rear ends me, I know help will be on the way. Flares are frequently needed at crashes too. I wouldnt keep any expired star shells in there though.