The following is a link to a 10-minute SciShow video, which describes
several cases, not of unusual fossils, but of fossils found in unusual
places:

<https://www.youtube.com/watch?v=2k7----LFJ8>

1: Triamyxa coprolithica is the only known species of this family,
found fossilized in a coprolite.

2: A fossil Centuriavis lioae, a turkey-like bird not previously
described, was originally found in Nebraska 1933, then tucked in a
drawer in the Bruce Museum in Greenwich, Connecticut, and forgotten
until 2019.

3: a customer of a restaurant in Sichuan, China, looked down at the
floor and noticed the large stones had multiple impressions of
sauropod footprints.

4: a plethora of fossils around Jura Mountain wineries, which are said
to give the wines their unique bouquet

5: In 2022, a group of scientists published their analysis of
thousands of fossil teeth belonging to 10 previously unknown species
of ancient rodents that lived around 33 to 35 million years ago, found
while sorting through the pebble cover of harvester ant nests.

Not mentioned in the above video is the story of how the first
identified Ediacaran fossil was discovered, not in some wilderness a
bajillion miles away from civilization, but in Charnwood Forest near
Leicestershire, England, and not by some multinational power team of
experts, but by then schoolboy Roger Mason in 1957 who lived nearby.
An irony is, nobody bothered to look for fossils there, even when then
schoolgirl Tina Negus reported seeing them 1956, because it was
considered at that time the rocks were too old to contain fossils.