This quarter has a large bump on the obverse. The back is perfectly flat with no dents or problems. Is this an unusual cud error or maybe a planchet error?
I agree with the others that it is heat related damage. I've seen several coins over the years that had those bumps. Some had obviously survived a fire, others were not so obvious...
We had a house fire in 1989. Our entire collection was in the fire. (it burned to the ground). We detected for days to find all we could (we knew where the "fireproof safe" (that wasn't really house-fireproof) was, so we were able to get most of it. The gold was fine, of course, all the fractional currency was gone, (not really gone, you just couldn't pick it up without it falling apart), but more quarters than halves or silver dollars got those darn heat bumps on them.
If you put your stuff in a fireproof safe - make sure it is really a fire-proof and heat proof safe. We found out, the hard way, that alot of safes have the latch made of something NOT fireproof. It melts, and "bakes" anything inside. Turns it into a kiln. Make sure you get a safe like Sentry makes (a little more expensive variety), that has fireproofing OVER the door latch, so the latch cannot melt.