Setting: The scrubland desert. Gravel and sagebrush and box canyons. Hardpan and painted mesas. Roll d10.
1: Skinny coyotes scamper through camp, running straight for any available foodstuffs or scraps, trying to carry them away. The coyotes will dodge the PCs, but if left unmolested will tear into bags and rucksacks to get at anything within.
2: A night wind blows, pregnant with dust and static electricity. Everyone is irritated and edgestrong but can’t place why.
3: Somewhere in the foothills a sullen black storm has broken, and snake-fast water rolls down the arroyos toward camp, impossibly fast and ugly.
4: As the party moves through a narrow slot canyon, black handprints line the rock walls. Each has a thumb and four fingers.
5: The party stumbles upon a cache of supplies. Well, contraband. Something with high bulk relative to value: tobacco leaves or liquor or bales of unrefined spices. If the party is still around in 1d2 days, a group of horsemen and a muleskinner leading pack mules will arrive to recover the cache and take it where it was going.
6: A set of fresh tracks–deep and clear and barefooted–suddenly appear, carry on for several hundred yards, then disappear again.
7: There’s a campsite ahead, with a brushwood lean-to and an old fire-ring, bedding and campstools. Sitting on the stools are three mannequins made of sticks and burlap sacks stuffed with dry grass. They sit facing exactly away from each other.
8: Someone has dug foot-wide trenches down through the light-colored dirt to the darker earth beneath. If they were for irrigation, they might lead somewhere, but they don’t. Careful mapping or a high promontory will reveal that they make up enormous sigils of no recognizable design.
9: Thousands of tarantulas, the size of a man’s hand, are migrating like a black woolen blanket along the hardpan across the party’s path.
10: Up in one of the box canyons there’s an old scrub oak draped with women’s undergarments.