The banks of the Thames and plenty of other rivers will offer the same finds as the beach, be it Sea glass, Hag stones or fishing net floats if you are really lucky, they make great Witch balls. I havn't been THAT lucky though.
All the Hag stones I keep to ward off evil intent, be they on my Sea Witch style Altar, key ring or nailed to my front door next to Horse Brasses came from the Thames bank, no need to go to the coast!
I wouldn't have to much faith in the Horse Brass I came upon recently though, featuring Tower bridge it was named on the Brass as London Bridge, it seemed that this brass was made by someone beyond help! Horse Brasses are excellent for warding off the evil eye, after all, that's what they where made to do.
To date I have only found one horse shoe, under Tower bridge and now nailed above my front door, but if you extend to old bones you are spoiled for choice, they abound.
However, it's not all finding, a few nights ago I went to Tower bridge and threw a matchbox containing a note with all my current troubles in it down into the river for the tide, river and waning moon to carry off, and I can't think how many silver coins lay on the rivers bed, a wish being made first. Those who throw them into the Tower of London moat at the 'Traitors gate' must be making someone really happy....they all vanish again whenever they drain it!