We just came back from Abbotsford BC and I was fascinated by all the blackberries that grow wild along the roadsides, in empty lots and along the fences. The roadsides are just loaded and obviously no one is interested in picking these delectable fruits that are free for the picking. Mind you, you need a suit of armour to get into the middle of that bush where the best and biggest berries are. These berries grow on the thorniest bushes you can possibly imagine and that is not an exaggeration! The thorns literally grab you and entrap you so that you need to physically extricate yourself from their tenacious hold. But I tell you, those berries are worth the battle. When ripe, they are so sweet and juicy and they literally just fall into the palm of your hand.
The red ones in the top picture are not yet ripe but the picture shows you how prolific they are. The bush in lower right is positively black with ripe berries. The middle picture on the left is a close-up of some ripe fruit.
We found the the ones that fall into your palm at the slightest touch are VERY sweet because they are so ripe. If you have to pull them off, they are sour! I guess that is why the store bought ones are always so sour -- because in order to withstand the shipping, they have to be picked before they are fully ripe.