I was an 8 year old awash in fossils, so I was a tad more generous than this former 9 year old PEI lad with his much more valuable fossil. I donated a lower mandible piece from a ~12,000,000 year old Saskatchewan rhino to the Sask. Natural History (now Royal Sask.) Museum in the 1980s. I too used plastic bristle brushes (AKA tooth brushes) to dust off fossils I collected from the surface of a gravel pit near Wood Mountain, SK. Many more fossils and fossil fragments from that pit have since ended up in cement in the area.
Wood Mountain is one of two locations in Saskatchewan which weren’t significantly affected by glaciers from the last two ice ages. This left glacially tilled soil, rock, and fossil bits in the gravel pits of the area. When I was a boy, I’d sometimes play on the gravel pile my parents had brought in to make cement for our garage floor. I noticed odd rocks, and one that looked like it had teeth, so I set it aside, beside the south wall of the house. A year or two later, we took the biggest fossil to the RSM for them to look at it. They identified it, provided me with a copy of the ROM’s scientific description of the extinct animal, and accepted the fossil into their collection.
A few years later I found a larger fossil from an older rhino, and they assembled it for me.