He's gotten into some early bog blueberries and probably a couple of crowberries. Nothing that is going to kill him, just leave him very, very miserable for a bit. For @Craw.
Having crawled out of the den with an empty stomach, leaving @Kara to continue to sleep soundly, the boys blue eyes took another pass at the clearing that surrounded their den. The grass was short and tight, perhaps grazed by some great wild wooly before the wolves moved in (never mind how it would have gotten up there, goats being the most likely culprits). Nothing for a boy with aching gums and an empty stomach to wrap his teeth around. A little further out, was a small stand of bushes that he had paid little mind to when they were covered with little pink blooms. Perhaps a stick would do the trick?
As he drew closer, it became clear that some of the flowers had withered away and in their place stood bright black berries. A quick glance across the flat top of the monadnock showed a big black bird perched on another of the bushes, picking out the berries with his long back beak and swallowing them whole. The boy decided if the bird (clearly a grown up) thought they were ok to eat then he could too. Tentatively, he ate one - his nose wrinkling at the tartness of the berries not quite ripe for picking yet, although, they weren't entirely inedible. Gritty from the seeds and a little dry - but it was more than he had in his stomach for now so he continued to pick the bush clean. From there he moved onto the next until his stomach swollen with under-ripe berries gave an angry growl.
Something was wrong. Something was terribly wrong.
Maybe he should just lay down for a moment, perhaps try to sleep it off. His face was twisted into a grimace as his stomach continued to roll and bubble.