I always bring my own tea (loose leaf, often in a ziplock baggy) with me when I travel, including to the Netherlands (and other int’l destinations). In the past I’ve had it in my checked bag, but my luggage kept ending up delayed, so I’ve started bringing it in my carry-on. I recommend if you do bring your own coffee that you bring it in the carry-on.
Since it’s not a liquid or propellant or any sort of banned substance it won’t be a problem. And, in fact, carrying on a coffee can is also permitted..but as @Trillian points out people who are trying to bring in illegal drugs have been known to place coffee in their bags to attempt to throw off drug-sniffing dog’s noses. So, this is why I suggest you don’t check the bag—because if your checked luggage is ‘randomly’ selected for TSA screening and has coffee in it..it could potentially be subject to more thorough screening (wiping down for traces of drug residue, waiting for the TSA agent with the K-9 to sniff it, etc.) and therefore, could be delayed slightly getting to the planeside..so you run the risk of having your baggage not arrive on the same flight as you.
True story – I brought back wonderful Venezuelan dark roast coffee (fresh ground) for my husband in my suitcase the same trip that I was also carrying back a brick of Panela for my friend Sarah. Sarah attended college in Colombia where Panela is something people drink in lieu of coffee or tea, so while I was in Venezuela my driver had his wife get me a brick of it (wrapped in cellophane—like Saran Wrap) so I could give it to Sarah.
As luck would have it, for the first time in over a dozen trips in and out of the country THIS was the day that I got picked for a random plane-side (at gun point!) screening of my luggage by Venezuelan military forces. At about the point that I was standing plane-side, with assault rifles pointed at me and minutes before they were supposed to close the boarding door it struck me: how stupid was I to have a “brick” of something brownish/white-ish sugar-y and a bunch of coffee in my checked luggage?
Not only did the Venezuelan soldier who went through my suitcase not bat an eyelash (he said: “Oh, Panela” and didn’t even open the saran wrap) I had no difficulty bringing it into the US at all, either. No problemo!