Mike,

Welcome to the fire! Sounds like you had a good family outing. Congratulations on getting the fire started using the fungus!

I'll admit I haven't used a magnifying glass to start a fire since as a little kid I started some mattress stuffing on fire but IIRC the general consensus here is dark tinders work best. White or lighter colored tinders reflect too much and so don't get hot enough unless you are pumping a lot of sunlight into the spot. Some people have reported rubbing a little dirt on cattail fluff works.

What sized fresnel lens were you using? One of those credit card sized ones?

-Blast