Gentle observation. Over the past week you have asked about a dozen questions about US stamp ID and values. Several of the replies have tried to guide you to the StampSmarter website or the Scott US Specialized Catalog to encourage you to learn how to ID your stamps on your own. These two resources are excellent starting places for the information you seek.
I suggest this because, the stamp you post above is perf 10, yet you are asking if it is a 544 which is perf 11. An impossibility. When trying to ID a Washington/Franklin stamp of the 1908-22 era, the first step is to throw away your ruler. The second step is to really throw away your ruler. The third step is to accurately measure the perforation rate. This eliminates a lot of the false possibilities. Then onward to other steps such as watermark and printing method and engraving type. There will seldom ever be a need to measure the dimensions of the image.
Now, knowing this is a perf 10 stamp, what Scott number do you think it is?
K-E, As you can see, we would rather teach and guide you to ID your own stamps rather than giving you final answers. And indeed we usually cannot tell a watermark from an internet image - as in this case.
You can ask all the questions you want. No problem. But learning to do some of the fundamental basics - like checking perforations & watermarks - will make your job a lot easier.
For example, the 1c Washington in this thread is obviously a perf 10 - which can be seen even from the picture. Get to know & love your perf gauge - it will help ease the mourning of your ruler!
You're also assuming every one of your stamps is a rarity. The common stamps were printed in the billions; the rarities are rare - with printing quantities in some cases less than a few thousand. Chances of finding a 'rarity' by chance is less than getting hit by lightning - while on your way to collect a winning lottery ticket.
Hard vs Soft paper is a different skill. Easiest way to check is to hold the stamp up to a strong light source. If you can see light through the stamp, it is hard paper; if the light doesn't penetrate the stamp, then it's soft. If you're not sure, take a photo and post it...
Cell phone pix of stamps are rarely good enough to tell anything other than the basics. Scans are much preferred...
Like this post. Kevin-Eric; I think you've been gently and quite correctly nudged in the direction of helping you identify your stamps on your own. No idea if you have a Scott catalog, but that is a great reference for identifying most every US stamp. I've spent hours looking up and identifying a large US revenue collection my dad had from his childhood; the enjoyment was just knowing what the heck he'd handed me after literally hours of learning what the heck "playing card" or "wine" stamps were all about as an example. The most valuable stamp is worth about ten bucks on eBay; what I learned was worth a lot more just as a collector and understanding what my dad handed to me.
If you are looking for that diamond in the rough to cash in, likely not going to happen. Not to be negative, but it is pretty rare that someone stumbles across the proverbial attic find that is worth thousands.