Arizona is a variety of climates rolled into one state. We have the advantage of mild winters in the south, snow in the north and east, and very nice summers in the north and east while the southern portion of the state is an oven. Arizona is prone to wildfires due to drought, dense forest areas with dead foliage, and heavy lightning storms from the monsoons. The emergence of blackberries often result from past wildfires. Wild blackberries can be found in several areas along Oak Creek, just above Sedona, and in several areas near the Mogillion Rim, around Payson, Strawberry, Pine, Heber, Taylor, and Snowflake. Basically, they can be found sporadically south of Flagstaff, east of I-17 to New Mexico in the forest areas. Wild blackberry patches are not mapped out and it's usually people who are familiar to the area, hunters, or those who just happen to stumble upon a blackberry patch, who get to enjoy the fruit. Arizona wild blackberries look just like the variety you find in your local grocery store, only smaller. Blackberries start out small and green, progressing to a light red and then ripening to a very dark purple. The most ideal time to harvest wild blackberries in Arizona is July-September.
I have eaten wild blackberries straight off the bush with no ill effects. We've also picked so many before that we've lightly crushed them in a ziplock and used them as fruit topping for pancakes in a camping trip.
I did forget to mention a couple of things. Watch out for the thorns and berries means bears, so be very aware.