PHILADELPHIA -- This summer, there must have been a dozen patches around the tiny borough of Narberth, Pa., sporting huge sunflowers.

It was no accident. The supersize sun-lovers were grown from seeds swapped among neighbors earlier in the year at Bob and Dawn Weisbord's house, as part of the Narberth Greens Flower and Vegetable Exchange.

"A big group of people came with lots of seeds," says Bob, who founded the exchange in 2008.

It may not be a new idea. But how neat is that?

At one time, collecting and sharing seeds was more about saving money than anything else. Today, it's likely to be that and more.

You might want to plant that great-tasting squash again next year, or preserve a hard-to-find plant. You might want to stand up for heirloom or older varieties, which are enjoying a resurgence.

Or you might be a gifted horticulturist like Gene Spurgeon, a retired architect, who enjoys the challenge of propagating hundreds of plants from seed (and the occasional cutting) for the Philadelphia area Hardy Plant Society's annual exchange or the Rock Garden Society's flower show exhibit.

Spurgeon, who's self-taught, works out of a rather luxurious "shed" he designed, along with his home, in Swarthmore. He collects seed for about 50 plants, among them carex, a carefree ornamental grass for shade, and unusual trees like Franklinia alatamaha, discovered by John and William Bartram in Georgia in 1765, and dawn redwood, which dates to prehistoric times.

"If I were a professional botanist, this would all be child's play," Spurgeon says, "but for someone outside that line of work, it's fascinating."

He adds: "It's also the pleasure of growing something you didn't have before, getting it into the garden, and walking your friends through and saying, 'I grew that from seed."'

Seeds are collected when plants are finished flowering. They need to be washed, dried, labeled, and stored in a cool, dark place. Depending on the plant, seeds can be started indoors under fluorescent lights in late winter or sown directly into the garden in early spring.

Seeds, like plants, vary tremendously. They range from near-microscopic to jumbo jet, and come in every shape you can imagine -- round, flat, big and fat or long and thin, with tufts, tails, wings.

Dawn Weisbord marvels at the oddball love-in-a-puff (Cardiospermum halicacabum), a fast-growing vine. Its three-sided seed pods look like pumped-up green lanterns; the little round seeds have white hearts on them.

Squeeze the pod and out pop the seeds, which can be started indoors eight weeks before the last frost or sown directly in spring. Actually, says Weisbord, an acupuncturist who grew up on a farm in Easton, Md., love-in-a-puff will reseed itself.

"But I like to collect seeds," she says. "There's something about the whole circle of it, like seeing it sprout and flower and then go to seed again. It's like doing all four of the seasons."

Wendy Flegal, Weisbord's neighbor, is one of many gardeners enamored of the intense fragrance and color of old-fashioned sweet peas. She likes the perennial version, which her grandparents grew, but she also has warm memories of the annual ones, which flocked the hillsides of Clearfield, Pa., when she was growing up.

"For me, it's an emotional connection, something to pass along, that will endure in a kind of hidden way," she says.

Flegal, who's retired from Temple University Center City, also collects larkspur, cosmos, columbine, and forget-me-nots, whose seeds, like many others, can be shaken from the pods onto a piece of white paper or into a paper bag. Forget-me-nots remind Flegal of shiny nubs of anthracite coal, the industry that used to employ her dad.

"I love looking at the seeds. They're tiny, gorgeous little things," she says.

Diane Ehrich collects seeds as part of her job managing Collins Native Plant Nursery in Glenside. "A lot are surprisingly easy to grow," she says, citing three beautiful but underused shrubs -- silky dogwood (Cornus amomum), red osier dogwood (Cornus sericea), and sweetshrub (Calycanthus floridus).

She pots the seeds in sand and sphagnum moss, keeps them outside in winter under screens, and plants them in spring.

"I used to want the instant gratification of buying a really large plant that gave me an instant, full, lush garden," Ehrich says, "but I love the whole idea of slowing down and realizing that these things take time."

Another insight: "Collecting seeds and growing them does connect you to a place."

Which is one of the ideas promoted by Seed Savers Exchange in Decorah, Iowa, through its heirloom seed bank, exchange, and catalog.

Membership jumped 40 percent this year, to 11,000, which John Torgrimson, the exchange's publications editor, thinks is partly due to the increase in new home gardeners -- 19 percent in 2009, according to the National Gardening Association.

It may also reflect a longing to reconnect with the food and flora culture of our grandparents, who collected and shared seeds of nonhybrid flowers and delicious vegetables that remain memorable over time.

Who could forget the "outhouse hollyhock," a fixture on American farms for more than a century? "Refined ladies just looked for the hollyhocks and didn't have to ask where the 'outhouse' was," Torgrimson says.

And picture the rainbow or five-color silverbeet Swiss chard, with its leaves and stalks of orange, pink, crimson, silver-white, and yellow. It was dropped from commercial catalogs in the late 1980s and revived by Seed Savers.

"It's a great-tasting chard, but its unusual color is the thing. It's become a best-seller," Torgrimson says.