I enjoy a good search....and the one place in the US that has chervil root is out. You might email them and ask about a packet? Otherwise, here's the place I found that will ship to the US at £25 in shipping. Eeek! However, I am happy to get together with you to all order at once and split the shipping and someone divide the order and ship the rest to the other person domestically.
https://www.otterfarm.co.uk/product/chervil-root/