Ehh realistically I bought the beginner bundle in the premium shop and my Kickstarter companions make decent pebbles when bonded, but beyond that honestly leveling up and grinding to sell any non food or useful crafting items. Also the gauntlet can net decent pebbles if you're strong enough.
Right now there's not many ways, but as people get more food and bigger packs it'll make the grind a lot easier to get better items as the campaign goes on.
Edit: also doing endless dailies as I can muster energy for the wolves, or have enough resources.