Playing in a game (modern setting) where my character has a sacred bundle/spirit bag/set of totems, all things that he has found. Now, the items themselves have no real metaphysical/magical properties but the character thinks that they do. I can come up with the New Ageish properties of the various rocks and minerals, but can't really think of reputed properties of the other items. Any ideas of what properties the character might think the following items have?  Or possible believed properties of other interesting mundane items.

01) part of a turtle shell - red-eared slider - Tenn

02) seed from a red buckeye - Mississippi

03) small redwood twig - California

04) frosted piece of purple beach glass - Oregon

05) thorn from a black locust tree - Georgia

06) antique square nail - Illinois

07) old brass house key - Washington (the state)

08) sea shell, scallop type - Florida

09) old Orange Crush bottle cap - Ohio

10) flint or chert arrowhead - Missouri

11) old marble - Kansas

A quick list based on some quick research and some tales told

A turtle shell: Longevity, order and stability.
A buckeye: Luck and male potency.
A redwood: Healing.
A beach glass: All four elements.
A thorn: Healing.
A key: Opening and closing paths of power/knowledge.
A shell: Travel or movement
A bottle cap: Sealing things in, or delivering curses
An arrowhead: warding against evil.
A marble: All four elements.

Excellent!  Thank you very much.  This is exactly what I need.  Anyone else with thoughts?

My thought was that you didn't need an explanation for everything. The character may pick up an item because it "feels right" or has a certain feeling of power. Then in game, play reveals (or your imagination fills in) the details of the connection that your PC subconsciously sensed when they picked up the item. So if your character (or even another character with you) successfully picks a lock or finds a door that is unlocked your character rationalizes the success or state of affairs as being caused by or influenced by the fact that your sacred bundle contains the brass key.

Nail - As I recall, a nail can provide protection against fairies. It might also be useful as a substitute for a pin when performing some type of voodoo-doll curse.

Nails have also been used as a protection or even curse against witches. A horseshoe nail made into a ring I saw long ago. Theres also healing ascribed to nails, or luck. Even the nature of the nail can change the properties, like a bent nail is used as a ward and a rusty nail is used for luck.

Regional is the key here. Were is the character from? That will likely effect some of their beliefs. For example where I lived the buckeye was a good luck charm. Never heard of the other properties till moved out of state.

The AD&D DMG gives some properties to various materials.

And as pointed out above. Personal belief can trump all. If someone believes a penny found is good luck then it doesnt matter if its heads or tails.

Or a personal example the mystery marble I have. To me it represents impossible luck because I found it along with an item I had lost TWENTY-FIVE YEARS AGO while taking one last walk around my home town before having to move cross country.

Thanks for these excellent ideas Omega and Bren.  I can really make use of them.  For the character, he has moved around his entire life across North America, probably never spending more than a couple of months in any one location at a time.  The regionalism comment is correct, lots of different beliefs in different places, most of which came from other far away locations and mixed and combined with each other.

I added the places he found each item above if that makes any difference.

The key here though is probably not where he found the items, but where he himself is from. The attributes ascribed there will tend to be the ones he picked up and now associates. Which leads into Brens note that belief can trump all. so if he grew up believing a piece of drift glass is a weather charm then doesnt matter what the locals believe.

Also the circumstance of findng an item can shape the holders belief in what attributes it has. Such as there was a storm brewing, he found that piece of drift glass and the storm stopped right after.

Very good points Omega, and something I'll add to what and how the character believes.  If nothing else, this thread may be good to spark an idea for others.

If you're interested in this thing generally, you must have this book.  The Funk & Wagnalls Standard Dictionary of Folklore, Mythology and Legend is long out of print, but you can get copies on Amazon for as little as $7.  It is a frigging diamond mine for the GM, just under 1200 pages worth of folklore and legend from around the world.

The entry on keys, for instance, is nine paragraphs long, ranging from discussions of their mythological significance to a key's folkloric influence in various cultures: that in traditional practice, a key in Germany was used as an amulet against the evil eye; in Italy, tiny ones are put on babies to stave off convulsions; in Norway, iron keys were hung over cattle barns to cure bewitched cattle and brass ones over fields to "lock out" hail; in China, given to an only son to "lock him into life."

Probably not easy to find now, but well worth it.

Thanks for that, I will be ordering a copy.

In ancient china, turtle-shells were used for divination.