Biennials are wild and free - some people like this - some people don't, but no matter whether the free food is a perennial, an annual or a biennial, it's still food.
The free part means these plants either eaily and readily reseed, multiply by runners, crowns or rhizomes, basically they just keep on multiplying - something a plant does well.
Beetberry - aka Strawberry Spinach or Chenopodium capitata, a favorite biennial of mine and pictured above. The leaves are delicious in the spring as a first year rosette and continue to be all year. Next year they will bolt - sending up a tall stalk with bright red berries clinging to the stem - yummy! They are sweet and juicy and seedy. If you leave some behind when you are sweetening your oatmeal they will reseed for sure. The whole berry dries on the stalk and drops when ready. Flash flooding delivers the seed all the way down the driveway.
Another favorite freebie is Mizuna - a snappy mustard ready to grow anywhere!