This is a great location for farming materials in the 60s as it provides you with the high in demand Asparagus as well as the normally great selling Platinum, Hard Wood & Elder Wood Logs. While a lot of Mount Maelstrom is worth farming there are only a few locations here that I found really stand out. The first one is Gauntlet Gulch in northern Mount Maelstrom just south of Gauntlet Waypoint. It's the first screenshot you'll see below.
This location has a ton of Asparagus amongst other things, all of which sell for quite a bit of money on the Trading Post. It's a bit dangerous to gather here depending on your level and where you go. No matter what level you are as you get closer to the beach the amount of Risen you'll encounter starts to become a bit crazy. I recommend avoiding the beach unless you have a death wish.
West of Gauntlet Waypoint in the caves (not shown on my above map) you can find a ton of Portobello Mushrooms. They don't sell that much but if you're a Chef they may be useful in the future for some cooking recipes. A bit southwest of Gauntlet Gulch you have Criterion Canyon, which is my favorite little location to gather materials in this level range. Really all over the picture I have taken below you'll find nodes of all kinds. I marked common locations on the map to give you an idea of what you'll be finding here.
The Platinum Ore and Hard Wood logs will be your best sellers here. They're the most common materials you'll be finding here and the only thing more valuable is the Asparagus, at least sometimes it is. Depending on how many people are leveling the Chef profession Asparagus may or may not be a big ticket item. Either way you shouldn't avoid gathering anything here. Everything is worth some money, even if you have to offload it to a vendor.
As for how much money you'll be making here, don't forget this is a 60 - 70 zone. So while you won't make bajillions of gold from farming here you will definitely be making a very reasonable amount of money which will help you afford whatever it is you're looking to buy. On average from gathering in Mount Maelstrom you'll net 75s to 2g an hour. Don't forget to bring your Magic Find food and be sure to loot the mobs you kill in the way of your gathering nodes, they can drop Fine crafting materials which are worth more than any gatherable material you'll find here.