Calendula flowers.
You can get good calendula flowers in bulk from the UK.
Pic: Bought vs. picked calendula flowers.
Here's a pic of two different batches of Calendula flowers:
1) Organic herb trading co. dried herb, from Spain, and 2) mine.
You can see that my calendula flowers are a little brighter, especially in the orange and green parts. But for bought calendula this is excellent quality: the color difference is small, and the smell of the bought flowers is not too bad. Nice!
I'm making another batch of calendula salve as I write this (earlier this week, as you read this), with the bought herb.
I'll be getting year-old calendula from a local pal in January; I'll put up a three-way comparison of color then.
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Related entries: Calendula salve - Yellow flowers: Calendula
Calendulas usually regress
Calendulas usually regress to smaller, lighter-colored flowers, in seeds. Funny that you got darker flowers from your seed, really.
Dyer's chamomile, Anthemis tinctoria, is only mentioned in the US Disp, and there it's a one-liner: "A. tinctoria L. is occasionally employed as a tonic and vermifuge in Europe."
Yes, it's used in dyeing things. Yellow, I think, but it could have been light green, too.