Favorite Unusual Spice

I usually make pulao (rice) with aniseed and black cardamom. If you are not familiar with these spices look at this http://www.rachnas-kitchen.com/peas-pulao-recipe/

It's an herb, not a spice, but I'm very fond of a Mexican plant called Pipicha- It has a strong flavor reminiscent of cilantro, and must be used cautiously. A plant can perfume a large area on a warm day. Unfortunately, it is very tender and i have so far failed to collect seeds from it. There's a lot of neat stuff from Mexico; the one you're most likely to run into is Mexican oregano (Lippia Graveolens) which has a flavor similar to true oregano, but with sort of pineappley overtones; also pretty tender, though not as much as pipicha.

I love using Provence epices (4 spices) made of pepper, cloves, ginger and nutmeg and in use since the middle ages. I also bought some Piment de'Espelette, which is a red pepper grown only in the Pyrénées mountains. It's not as spicy as regular red pepper.
I also love to use sumac, ras-el-hanout, and za'atar in my cooking. The spices add flavors I could never find anywhere else.

Kala jeera. Not sure why more US cooks don't use it. I get it from Penzeys in large bags and love it! ;o)

P.S. If buying from a bulk source such as an Indian grocery, get just a tiny bit and try it out with a small portion of dal. I've gotten bulk kala jeera that was not nearly as fresh and tasty as the Penzeys.

I have a recipe here on Food52 that uses it, if anyone is interested.

Incidentally, I asked Food52 columnist Brown Table for suggestions on other ways to use it, but he did not respond.

It might not be as interesting as a trip to Chile, but you can buy merquen on Amazon. Urfa biber is not difficult to find, but I ordered it from Spice Station in Hollywood, CA. It arrived in no time (to the other side of the US) and the service was excellent.

Here's a really interesting write-up on merken and the other wonders that region of Chile--it's responsible for out potatoes and garden strawberries! http://eccentricculinary.com/merken-the-mapuche-spice/

Not to deny you another trip to Chile, but merken (or merquen) is available from Zingermans.com.

Grains of Paradise - more floral, aromatic flavor than peppercorns but with (essentially) the same uses. I find myself adding a smidge here and there, in both sweet and savory dishes.

What's unusual to one may be everyday to another, so not sure what to call "unusual." Love Raz-el-Hanout. I use mace and cardamom so often (especially in baking) that I don't think of either as "unusual" any more.
And I love to play with the various masalas that non-Indians think of as "curry." And not always for Indian food.

It's not all that exotic, but I really like szechuan peppercorns. So tingly and numby on the tongue! Also, I'm seconding the 'smoked cinnamon' suggestion. Try it in some homemade applesauce and use on pork if you want a real new kind of taste. Very cool stuff.

Thippili / Pippili known as Long pepper. This was an ancient spice that predates the regular black peppercorn.. Its has a fantastic unusual flavor that I can't quite describe.. REcently discovered that there were actually 2 varieties of the same spice.
https://en.wikipedia.org/wiki/Long_pepper

I'd say za'atar, but I think it's technically an herb, so I'll go with sumac.

I love mace, it's a skin of nutmeg, but not nutmeg at all. I love to use it in curries and sometimes in the winter when I am baking.

I actually use sansho and ichimi togarashi from the Japanese grocer frequently. Sansho is a popular table seasoning for grilled foods in Japan in the summer, supposedly helps prevent fatigue in the summer, and is often on or brought to the table at eel restaurants.

Ichimi togarashi is one of those chilies with a slow, lingering heat that builds but never gets too hot. Sansho has that faint citrusy quality with the numbing tingly effect similar to Sichuan pepper/prickly ash, but I find that it is easier to get relatively fresh(er) sansho than sichuan pepper if you don't live near a Chinese grocer.

Since you love cinnamon, you should try smoked cinnamon:
http://shop.laboiteny.com/products/smoked-cinnamon-n-18
I've only read about it, but I definitely need to try it.

Hawadj (also spelled hawaijj) a savory blend from Yemen, including pepper, cardamon and cumin. Love it in stews and soups.
Also cardamon, for use in coffee and in spice cakes.
Last, Aleppo pepper (from the same region as the Urfa pepper already mentioned).

I love merquén (the other spelling for merkén and the one I knew). When I use mine up I'll just have to go back to Chile.
Another spice I enjoy that's less common than some is Urfa chile (aka Urfa biber or Isot pepper). It's a sun dried mild chile from Turkey, with a fruity-smoky flavor that's particularly great on roasted vegetables.

it's more of an unusual ingredient (?), and many would see it as slightly low class, but i really like cooking with french's yellow mustard. it is so tart and makes a nice base in which to add garlic and other spices/herbs to smear on lamb and chicken. i also like the warmth of cardamom especially on honeyed spiced nuts and recently i got a little jar of dried ground specialty peppers (not too hot) from the farmers market. i still don't like cilantro though (sorry).

I don't know how unusual it is anymore, but I love using berbere spice on chicken and lamb (especially). Its curry-esque and I LOVE curry.