Here's what you do:
Find a lovely hillside or meadow where the air is clean and the water is pure and look for the tall stalks of the milkweed plant sticking up amidst the long grasses and wildflowers. Go now, before the beautiful, beaded pale green clusters bloom into wonderfully fragrant mauve flowers. Take a cotton tote or a plastic bag and pinch off the buds, being careful not to disturb any Monarch butterfly cocoons. Make sure not to denude any stalks and to leave plenty of buds behind.
Milkweed tends to grow in great patches, so it shouldn't be hard to forage sustainably. Your fingers will become sticky from the white latex that oozes from this plant wherever you break it. Thistles and nettles may grow nearby. Dragonflies will dart around you, glistening in the sunlight. Take what you need for dinner and move along.