Here’s a list of plants that have been reported as safe for rabbits. I have personally fed most of these to my rabbits with no ill effects, but not all of them. I’ll be trying them all out so I can say for sure but in the meantime, give it a go!

Alfalfa Medicago sativa Above ground parts.

American sycamore Platanus occidentalis Leaves, twigs, bark.

Apple Malus domestica Leaves, branches, fruit. Seeds are toxic.

Basil Ocimum basilicum Above ground parts.

Blackberry Rubus spp. Above ground parts.

Borage Borago officinalis Above ground parts.

Carrot Daucus carota sativus All parts, except seeds.

Cat-tail Typha latifolia All parts of the plant are safe.

Chickweed Stellaria media Above ground parts.

Chicory, wild Cichorium intybus All parts.

Cilantro Coriandrum sativum Leaves, stems.

Clover, red Trifolium pratense Above ground parts.

Clover, white Trifolium repens Above ground parts.

Comfrey, common Symphytum officinale Leaves. Best dried.

Dandelion Taraxacum officinale All parts.

Crape Vitus spp. Leaves and vines.

Hackberry Celtis occidentalis Leaves, twigs.

Jewelweed Impatiens capensis Leaves, stems.

Kudzu Pueraria lobata Above ground parts.

Lambs-quarters Chenopodium album Above ground parts.

Lemon balm Melissa officinalis Above ground parts.

Mallow Malva spp. All parts.

Maple, silver Acer saccharinum Leaves and branches.

Maple, sugar Acer saccharum Leaves and branches.

Mesquite Prosopis juliflora Leaves and twigs.

Mint Mentha spp. Above ground parts. Not to pregnant/nursing does.

Mulberry, white Morus alba Leaves, twigs, small branches.

Nettle, stinging Urtica dioica Above ground parts. Must be dried.

Parsley Petroselinum crispum Above ground parts.

Pear Pyrus communis Leaves, branches, fruit. Seeds may be toxic.

Pigweed Amaranthus albus Leaves, stems.

Plantain Plantago spp. Above ground parts.

Purslane Portulaca oleracea Above ground parts.

Queen Anne’s Lace Daucus carota All parts, except seeds.

Radish Raphanus sativus All parts.

Raspberry Rubus idaeus Above ground parts.

Redroot pigweed Amaranthus retroflexus Above ground parts.

Rose Rosa spp. Above ground parts.

Shepherd’s purse Capsella bursta-pastoris Above ground parts.

Sow thistle, annual Sonchus oleraceus Above ground parts.

Sow thistle, perennial Sonchus arvensis Above ground parts.

Sow thistle, spiny annual Sonchus asper Above ground parts.

Squash Curcurbita spp. Young leaves and stems, fruit, seeds.

Strawberry Fragaria spp. Above ground parts.

Sweet potato Ipomoea batatas Tubers and vines. Rich and fattening.

Sunflower Helianthus annuus Above ground parts.

Willow Salix spp. Leaves and branches.

Wing stem Verbesina alternifolia Leaves, flowers, stems.

Yarrow Achillea millefolium Leaves, stems. Not to pregnant/nursing does.

List taken from https://rabbittalk.com/threads/safe-plants-for-rabbits-list.55/