My daughter has recovered a plant from her grandmother's house in southern Ontario that my wife says has always been referred to as "pot cheese" because the flowers just before they open look like little curds of cottage cheese. My wife has always wondered what it really is, mostly because she's worried about losing this ancestral plant if something kills hers. Can someone help from the pictures I'm attaching? My daughter reports that it's about 16 inches tall. The flowers are not fragrant like Meadowsweet, but it certainly looks related. Don't be fooled by the leaves in the pictures with the hosta background and the grape vine crossing in front. The second picture isolates the leaves better. The third one tries to get a closer view of the flowers, and the fourth succeeds.
As Vince Bowdren figured out, the plant is Filipendula ulmaria, sometimes called Meadowsweet or Queen of the Meadow (although there are several completely unrelated plants also called Meadowsweet, which can be confusing).
Normally Filipendula ulmaria has a strong floral odor. However, yours appears to be a double-flowered variety. In a double-flowered plant, the flower has mutated so that instead of the normal interior floral parts (stamen and style), it makes extra petals. If the perfume was produced on one of the parts that mutated into petals, the double-flowered variety wouln't have any perfume. (Different plants produce perfume in different plant parts; some have glands on the leaves, or stem, or inside the flower itself, so this would be different in different plants.)
I had a very difficult time finding any descriptions of double-flowered varieties with close-up photos for comparison to yours. The only double-flowered variety I could find with a photo is Filipendula ulmaria 'Flore pleno':
Yours might not be that exact variety, but it will be difficult to narrow down further without better references than I could find. Since you've had this plant for so long, it might be a different cultivar than what is currently available on the market. If you want to try to figure out the exact variety, see if you can find a local/regional gardening society with excellent knowledge of plants used in gardens of the era when yours was planted. Maybe a long-standing botanical garden of the area.