Yes. All the time. Just ask.
When I've called people who have homes for rent, about 30% of them are willing to do rent-to-own.
When I've called people who are selling their homes, the percentage is lower, but some certainly will say yes.
There are plenty of techniques to finding the right owners. Here are a couple:
Look for vacant properties. If it's a rental, the owner may be getting so anxious that he/she will consider selling it. Same idea for properties for sale; if it's empty, they're willing to to rent now (for the cash flow) and sell later.
Deal with the owners themselves. Don't deal through real estate agents. (Most will strongly discourage you from making the offers. And the listing agents will strongly discourage the owner from accepting the offer.)
Make it easy for the owner. If, for instance, you're approaching a landlord, especially one with a vacant property, your pitch is: "If I could give you more than you're asking for each month, and if I took care of all maintenance and upkeep on the property, would you consider selling me the property in a few years?" Offer above-market rent (with the extra credited to the purchase price) and offer to handle all maintenance and repairs. (Tip: Buy a homeowner's warranty for about $400 a year. Then there's only a deductible of about $90 for each problem that you need serviced.)
There's a lot more to it, of course. But the simple answer to your question is: Yes.
Hope that helps.