Don't get hung-up on value. Very few stamps are worth more than $1. Most are worth a penny of two at best.
Don't believe IDs or mounting placement from previous owners (In this case your 5 cent stamp is in the incorrect place. To send you in the correct direction, it is a Scott catalog # 586, which is perforated on each side at a rate of 10 holes per 2 centimeters, commonly referred to as "perf 10".)
There are often one or more look-alikes to the stamps you have - differing by some small facet which make a significant value difference. There is a good chance the other stamps on the page you show are mounting in the incorrect space.
Don't believe everything you read online. Sites like
ebay can be great sources of information AND disinformation.
Rare stamps are just that. Rare. The odds are extremely long of finding something of significant value in a $5 garage sale lot.
The "Antiques Roadshow mantra applies: Beyond the basic commonness or rarity, "Everything is condition, condition, condition". Just like coins and baseball cards in many ways
Ask us lots of questions, remembering the more you tell us, the more we can be directly helpful. (Thus the importance of knowing where you read the 5 cent stamp might be valuable so we can help you interpret it properly or guide you to a better resource.)
Invest in the basic tools to get the most enjoyment: tongs, perforation gauge, watermark tray & fluid.