JAPANESE DISCOVERIES
Earliest loom parts: Wooden components of a backstrap loom and clay spindle whorls have been discovered from a Late Jomon site (Yuusu phase) in Fukuoka City, north Kyushu. Dating to the 4th-3rd centuries BC, they are a century earlier than the known Yayoi examples. It is thought highly likely the tools were introduced with rice agriculture. (Source: Asahi Shimbun 30 Nov 93 retr. from SEAA)
Heritage of Japan 
What was their textile source and how were the fibers produced?
Local plant fibres, a variety of plant sources.
Interesting. Where was it found in Fukuoka ? Was anything else found such as skeletal remains that they could do a DNA test with ?
Yes, in Fukuoka