Although too early - there is nothing better on the planet - than wild blackberry jam. Make sure you are picking from areas that have not been sprayed.
You can tell the spots - generally avid blackberry hunters will have trodden paths through the tangled mess of blackberry and grass.
The recipe simple:
500 grams of Sugar
500 grams of wild Blackberry
Mix the sugar into the blackberry's - and bring slowly to the boil. Then simmer for 15 minutes.
Make sure your jars are sterilized in hot water!