Keven was wright"Heathergems, as the name suggests, is the brand name for jewellery made from natural Scottish Heather. The raw materials are twigs that are dyed and compressed together using weights to form solid blocks that are then cut into the various shapes required to produce the jewellery that you see in the shops. The jewellery is Celtic/Scottish by design."
They have store in Los Angeles, SAn diego and Santa Barbara. Maybe if you contact them, they'll sell you some.
I think Keven's way would be easier, Collect the heather dry it and die, Maybe you can stabilize it, compress it or cast it and sell us some