What are some materials that expand a lot proportionally to heat? There's never any source on the internet that can simply give me a list of materials that have the kinds of properties I'm looking for. I'm wondering what materials, like for a solid block of something, in general expand either a lot or at least very quickly when exposed to heat. I also can't remember what property this is exactly, but I think it's the coefficient of thermal expansion. 

Am I looking for something with a high coefficient or low coefficient to achieve this?
You are looking for thermal expansion and its coefficient.  Of course such tables, and diagrams exist



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as it is of relevance in daily live.  Thermometers based on liquid mercury, or alcohol, depend on this.  Bridges take this into account in expansion joints, too:



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Joining two materials of different expansion coefficient equally is of relevance for the design of bimetallic stripes, found not only in thermometers and mechanical clocks:



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So in reply to your "there is no source available" ...