Scrap silver can be found in such things as old electronic equipment, circuit boards, transistor radios and mobile phones as well as in dental, household equipment, cameras, photographic paper and plates, old silverware, cutlery and dishes, old broken jewelry and many other things.
Also old silver coins, known as junk coins, may contain silver especially those pre 1920s when silver was used as the main component part of silver coins.
Pure silver is obviously best and will bring the best price but even silver mixed with other metals is still saleable.
Old rings and jewelry is an excellent source of silver. Ensure you remove any gems or stones before you sell the silver. If the silver is mixed with other metals (not alloyed) then separate them if you can. Some may be gold and that can be sold also as scrap.
Walk in with a handful of scrap silver and a scrap merchant will welcome you with open arms. Most cities will have scrap metal dealers. Even jewelers are very likely to accept scrap silver.
You can sell scrap silver online of course. There are heaps of scrap merchants who will be happy to purchase your scrap silver form you. Ensure it is very clear what you are selling them. Taking photos of the scrap silver before you send it off would be a good idea in case of any later dispute. Sending the scrap deal a copy of the photos with the scrap silver is also a good idea.
If you have any unused old scrap silver around the place you can turn it into cash very easily these days and maybe even get as much if not more than you paid for it!