The blue fruits, sloes, are edible but only after the first frost, otjerwise they are to acid and astringent. They grow on a small very thorny bush, Blackthorn (Prunus spinosa).
It is very common in Perigord, you can find it at the limits of woods and along abandoned agricultural fields, especially on limestone soil. Blackthorn makes new stalks from its roots, and in a few years its branches can form literally impenetrable hedges.
Somewhat frightening!
But spiders love it.
Apparently it is a good home base for lichens.
It is one of the first Prunuses to flower in spring and it does this abundantly. Here below the flowers lost already their petals.
Only the little brushes of the stamens are still there. And now, we have to wait for fruits.