The laws surrounding foraging plants, mushrooms and shellfish in the UK are not exactly what you would call straight forward. When considering foraging somewhere there’s 2 main things you need to consider, the first is who owns the land and the second is if you’re allowed to collect whatever it is your foraging from it.
There’s several laws which apply to foraging in England and Wales, with Scotland having slightly different laws on some things.
The first thing to consider is who owns the land, and this relates to the laws of Trespass which states that you need explicit or implicit permission to access land not owned by yourself, unless you are permitted to do so by under the Right to Roam or Rights of Way act, otherwise you will be trespassing.
Scotland is an exception to this as they have the Right to Roam applied to the whole country, and the Land reform Act of 2003 includes confirms this.
This basically means that unless you are on public ground, you need permission to even walk onto the land from whoever owns it, unless there is a public right of way passing through it.
As for what you are allowed to take,this is covered partly by the theft act of 1968, and again by the Wildlife and Countryside Act 1981. The theft act states:
“A person who picks mushrooms growing wild on any land, or who picks flowers, fruit or foliage from a plant growing wild on any land, does not (although not in possession of the land) steal what he picks, unless he does it for reward or for sale or other commercial purpose.”
The wildlife and countryside act states it is an offence to uproot any plant from any land without permission from the landowner or any authorised person. This means actually digging up the plant and destroying the roots. For example, if you see a blackberry bush on public land you can pick all the berries you want, but if you dig you the plant you are committing an offence, no matter how common of a nuisance they are, its still technically illegal.
The final thing you need to be aware of is bylaws, which can remove the right to gather certain plants in certain areas. If one is in effect there should be notices on the entrance to these areas, and if so they normally restrict the gathering of a particular species.
Foraging Laws in a Nutshell
You are allowed to gather from any wild plant as long as the following criteria are met:
You are allowed to be on the land, which includes public ground such as parks and canals, or you have access due to a public right of way,or have permission to access the land from whoever owns it.
You are not taking anything protected in any way, such as endangered plants. You aren’t uprooting anything or damaging the plant beyond repair, which does not include cutting mushrooms at their stems as the underground part ensured the revival of the mushroom.
You are not using anything you take for commercial purposes, which includes making and selling your own jam. As long as what you’re taking is for your own personal use, you can forage as much as you like, with a few exceptions though, such as local limits imposed. For example on my favourite cockle gathering beach in Wales the limit is 1kg per person per day, though limits like this are rare and never apply to things like mushrooms and berries.
Heres a list of some of the protected or endangered plants listed in The Wildlife and Countryside Act 1981
Some more usueful link about the legality of foraging in the UK