A gourd is a fruit related to the squash and pumpkin. When mature, gourds become very hard like wood and can be used as a versatile craft product. Birdhouses, bird feeders, holiday decorations, primitive musical instruments, ornaments, and centerpieces are often made from gourds.
You can find gourds for sale on eBay. Here is a listing for 6 gourds ready to be used as birdhouses for Purple Martins:
Maybe you are a gardener or live in an area where you can grow gourds yourself. If so, consider growing some to sell on eBay as a craft item. You can also find gourds for sale at roadside fruit and vegetable stands, along rural country roads at country stores, at flea markets, or even at the farmer's market.