A list of dynamic accumulators I pulled off the nets....
Alfalfa: N, Fe
Apples: K
Arrowroot: Ca
Azolla: N
Bamboo: SiO2
Basswood: P, Ca, Mg
Beeches: K
Beeches, European: K, Ca
Birches: P
Birch, black: K, P, Ca
Bladderwreck: I, Mg, Fe
Borage: SiO2, K
Bracken, Eastern: K, P, Mn, Fe, Cu, Co
Brassicas, perennial: P, S
Bridal Bauer: P
Buckwheat: P
Burdock: Fe
Cabbage: B, Ca, Cr, Cu, Fe, N, K, S, Zn
Calamus: N, K, P
Caragreen: Na, N, Ca
Carraway: P
Carrot leaves: Mg, K
Cattail: N
Chamomile, corn: Ca, K
Chamomile, German: Ca, K, P
Chickweed, common: K, P, Mn
Chicory: Ca, K
Chives: Ca, Na
Cleavers: Na, Ca
Clovers: N, P
Coltsfoot: S, Mg, Ca, K, Fe, Cu
Comfrey: SiO2, N, Mg, Ca, K, Fe
Corn: K
Cornflower: P
Dandelion: Na, SiO2, Mg, Ca, K, P, Fe, Cu
Devil's Bit: I, Mg, Fe
Docks: Ca, K, P, Fe
Dogwood, flowering: K, P, Ca
Dulse: Na, I, Mg, Ca, Fe
Eyebright: S, K
Fat hen: Ca, Fe
Fennel: S, K, Na
Flax, seed: Ca
Garlic: F, S, P
Grasses: N, SiO2
Groundsel: Fe
Hickory: K, Ca
Hickory, shagbark: K, P, Ca
Horsetails: SiO2, Mg, Ca, Fe, Co
Iceland Moss: I
Kelp: Na, I, N, Mg, Ca, Fe
Lamb's Quarter: N, Ca, K, P, Mn
Legumes: N
Licorices: P, N2
Linden: P, Ca
Lemon Balm: P
Locust, black: K, Ca, N2
Lupine: N, P
Maples: K
Maple, sugar: K, Ca
Marigold, flowers: P
Meadow Sweet: Na, S, Mg, Ca, P, Fe
Mistletoe: Mg
Mullein, common: S, Mg, K, Fe
Mustards: S, P
Nettle, stinging: Na, S, N, Ca, K, Fe, Cu
Oak, bark: K
Oak, leaves: Ca
Oak, straw: SiO2
Oak, white: P
Parsley: Mg, Ca, K, Fe
Pecan: K, Ca
Pennycress: Zn
Peppermint: Mg, K
Pigweed, red root: Ca, K, P, Fe
Plantains: SiO2, S, Ca, K, Fe, Cu
Primrose: Mg
Pumpkin: K
Purslane: Ca, P, Fe
Rattan Palms: S, K, P
Salad burnet: Fe
Sanicle: K
Sarsaparilla: I
Savory: P
Scarlet pimpernel: Ca
Sheperd's purse: Na, S, Ca
Silverweed: K, Ca, Cu
Skunk Cabbage: Mg
Sorghum: K
Sorrel: Na, Ca, P
Sow thistle: Mg, K, Cu
Spurges: B
Squash: K
Strawberry leaves: Fe
Sugarcane: K
Sunflower: P
Tansy: K
Thistle, Canada: Fe
Thislte, creeping: Ca, K, Fe
Thistle, nodding: Fe
Thistle, Russian: Fe
Toadflax: Mg, Ca, Fe
Tobacco, stems/stalk: N
Two-grooved Milk Vetch: Se
Valerian: SiO2
Vetches: N, K, P, Cu, Co
Violets: P
Walnut: K, P
Walnut, black: K, P, Ca
Water Hyacinth: Cu
Watercress: Na, F, S, Mg, Ca, K, P, Fe
Willow, bark: Mg
Willow, black: Na
Wintergreen: Mg
Yarrow: N, K, P, Cu
EDIT: I noticed Walnut on the list. YOU MUST BE CAREFUL with walnut. It contains Juglone (C10H6O3). Juglone suppresses plant growth.