I went to the coal trucks west of mcgrubor woods, but no one's there anymore. I'm wondering is there a better place to mine coal now? I have 58 mining.

if no one is there, that means u have all the coal rocks to urself. mine there till 60 and then go to the mining guild

or get a dwarvenstout and enter the mining guild

Wow, I wish I had known this! Seriously, mine till your arms fall off!

 

 

 

You could also do the Throne of Miscellania quest and have the islanders mine coal for you. Keep them paid well, and you could have tons of coal in just a few days.

 

 

 

If you haven't done this quest, the mining carts are the best place to mine for coal. Ardougne has a few coal rocks to the east, but not as good as carts.