Sarutabaruta East, Sarutabaruta West and Yuhtunga Jungle with a "Rare" dig-up rate.
I prefer digging up these in Yuhtunga Jungle though, seeing how it also yields Petrified log and stuff :)
Yes they are worth selling on AH, you can get about 500g each more if you AH it rather than to sell to an NPC and it also allows people to skill up Woodoworking.
Right now (Apr 14-17, 2008) they're selling on the AH for 1k gil. To NPCs, they sell for 980g. I'll just save myself the time and trouble until people stop undercutting.