Your mom may have peanut butter that is literally only peanuts. You can make this kind yourself in a food processor or the machine they have in the store for making it. Peanuts only peanut butter is rather bland. So if you really mean natural, look on the label and be sure it contains salt. I think that even natural peanut butter also has other natural ingredients such as a sweetener. What they do not have is preservatives.
A comment about agave. Please research this ingredient. It is much better than high fructose corn syrup. It is made in an entirely different way. I is processed in a way similar to sugar from a natural food, agave. It is "all the rage" because it is natural and does not contain any other ingredient than agave and it does not spike blood sugar levels as sugar does. Also, you need to use less to achieve the same degree of sweetness as sugar gives. Thus it contains less calories/serving.
I don't remember why high fructose corn syrup is now considered unhealthy but I will look it up. There is disagreement about whether or not high fructose corn syrup is unhealthy. Moderation seems to be the key. HFC is currently found in excess in many processed foods. Whether or not it is unhealthy requires complex knowledge.
In a few minutes I found these sites. There are sites that dispute the healthy use of agave but not because it's the same as or similar to high fructose corn syrup HFC is made when the molecular structure of corn starch is chemically changed. Agave does contain fructose which is a healthy, natural sweetner. It is made by heating the agave plant to release the syrup. Sugar is made by heating sugar cane or sugar beets to release the syrup. Also, fructose is what sweetens our fruit. Fruit is a necessary part of a healthy diet. We do not stop eating fruit. If one believes all food should be raw then neither sugar or agave sweetener is acceptable.
In summary: HFC is made by changing the starch to fructose. In sugar and agave, fructose is the natural ingredient already present in the initial food.
http://www.mayoclinic.com/health/high-fructose-corn-syrup...
http://www.dvo.com/agave-nectar.html