My husband and I have a goal of visiting all of the National Parks, and each one we go to we grab a patch like those (all the parks have their own specific design). Each one we sew onto a square of cloth and add to a quilt (we have the in-progress piece on the wall in our bedroom) When we're done, I'll finish the quilt and hang it up! Maybe something similar would work for you?

Had to sign up to comment -- just saw this on Cathe Holden's site this morning -- a patch blanket! It's lovely. I love the quilt idea above as well.

http://www.scjohnson.com/en/family/family-economics/11-08-29/The-Patch-Blanket.aspx

When I was younger, I travled all over Europe and collected patches. I ended up sewing them all on a canvas bag. This would be a great library bag for him!

I'd put them on his backpack. That way he can share his stories at school, which would make him very cool...

Putting them in a frame reminds me of what my father used to said to my mom about using the "good" china:
"What are you saving it for? Your next husband?"

We saw more of the china after that.

Cut pennant style felt triangles and sew or use fabric glue a patch onto each one. Then, you can attach them to a ribbon and hang the flags as a bunting in his room. You can add as you go.

Each of us kids had a pillow case with different iron ons and patches growing up. You could put most of the patches on one side so he would not have to sleep with his head rubbing on the patches. I do like the idea of a quilt or even little shadow boxes but it can become overwhelming depending on how many you collect. another fun thing you could make christmas ornaments out of them. either glueing to a round ornament or placing a ribbon on the top of each one or even a safty pin so you could use them for something different too.

My idea is to do a series of small shadowboxes, with a few patches, a picture or two, and then a souvenir as well. The patches could be taped, and then used in a more permanent way when he's older. I had a large collection of "vacation jars" as a child, and making them was my favorite part of each trip.

I'm saving some of these for my son and I love the idea of having them as part of his room later. I'm thinking sewing them on some denim curtains or throw pillows will make a retro/travel room even more awesome.

I collect these. Right now I have them displayed on a cork/bulletin board and I like that they are out where I can see them, but not as risk of getting dirty. In high school I had a bunch of patches on my backpack and after a year they were utterly destroyed.

No idea if this would work for you or not, but we've taken these patches and sewn them on our daughter's Camelbak. They've been a reward for some of the hikes she's been on and it seemed fitting.

For a similar collection, I mounted them between glass and suede mat board. The texture and pressure kept things in place. However, it was a static collection and adding new patches may be more work than you want. It also may be too formal for a young child.

I’d get a nice box – maybe picked up at a travel location – where they could be stored for now. As a kid, I loved going through my boxes of treasures. And everything will be kept safe until he’s old enough to do something more formal.

Many of the National Parks gift shops sell Junior Ranger gear--vests, hats, etc. They're kind of insanely cute, as you can see from this example:
http://www.yosemitegifts.com/juraou.html

Maybe you could sew the patches onto a Junior Ranger shirt, along the lines of a scout uniform?

Have you ever seen those picture frames that are made of one sheet of glass and a flat back and held together with discreet metal clips? I used to have one that I used for "treasures" when I was teenager. As long as they aren't too thick, that should work.

Another idea is to use one of those wooden display cases with a hinged lid and a glass window. They can lie flat or stand up. I see them in flea markets/antique stores all the time. A lot of them are used by sellers to display small items for sale, but I bet plenty of them would sell the case. You could stand one up on a dresser, cover the bottom/back with small pieces of adhesive velcro, and attach the patches. They would be interchangeable, and it would be easy to add new ones.

I've been collecting patches from my travels and I have sewn them all onto a picnic rug. It's a great reminder, always a good conversation starter and even better - there is plenty of room still to go...

I like the denim curtain idea above and displaying them like butterfly specimens with straight pins in a shadowbox.

I would place them in rows in a large picture frame and then fill the empty spaces with images from places he'd like to visit, keeping the "wish list" images cut in the same shape. Something similar to this... http://www.etsy.com/listing/33245869/world-stars

Top a desk with glass with the patches under the glass

Picnic rug's the best idea ever.

Why don't you ask your son?

Ok...I would do a shadow box. I have a large vintage looking one from Restoration Hardware. It does not have a glass front and looks aged...that way my son can switch things in and out as he sees fit! Hope this helps!