I have received a B1/B2 visa and will travel from Denmark to the US.
Also, I searched for what foods you can bring into the US, but found the guidelines difficult to understand and rather vague.
You are right that the guidance is intentionally vague. The best guidelines are on the page Travelers bringing food into the U.S. for personal use (different rules apply if the goods are for resale or commercial use). That page has guidance on a number of common foodstuffs. The relevant entries:
-Tea- commercially packaged and ready to be boiled, steeped or microwaved in liquid. Coca, barberry and loose citrus leaves are prohibited (USDA Miscellaneous and Processed Products Manual, Table 3-148)
-Spices- most dried spices are allowed except for orange, lemon, lime and other citrus leaves and seeds, lemongrass, and many vegetable and fruit seeds
You can store it anywhere you'd like, but it's possible that the customs officers in the US will want to take a look at it, so I'd keep it somewhere reasonably accessible.
On your flight to the US, you'll be given a customs declaration form, where you can declare your foods. You may be asked to speak to an agricultural specialist as you turn in your form to exit the baggage claim area. If something is not allowed, it will unfortunately be taken from you, but there should be no penalty as long as you've declared it (as long as it's not, say, a brick of heroin), so it's good to err on the side of declaring anything.
You shouldn't have a problem with bringing chili powder or tea with you, in either your carry on or checked bagggage. However, if the chili seeds are for propagation, consult the Animal and Plant Health Inspection Service (APHIS) Fruits and Vegetables Import Requirements (FAVIR) database at www.aphis.usda.gov.
You would list them on the declaration card you are given on board the aircraft prior to arrival.
All travelers entering the United States are REQUIRED to DECLARE meats, fruits, vegetables, plants, seeds, soil, animals, as well as plant and animal products (including soup or soup products) they may be carrying. The declaration must cover all items carried in checked baggage, carry-on luggage, or in a vehicle.
Importing coffee, tea or spices for personal use
What are the requirements for importing coffee, tea or spices for personal use?
There are no restrictions on the importation of coffee, tea or spices for personal use, although they may be subject to Animal and Plant Health Inspection Service (APHIS) and Food and Drug Administration (FDA) inspections if a Customs and Border Protection (CBP) Officer suspects contamination or insect infestation of the product.
Please note that tea or spices containing fruit or vegetable leaves or seeds, including citrus leaves or seeds, are typically prohibited.
For convenience, here is the link to the General List of Approved Food and Plant Products.
