Almost all of our trips are suitable for kids accompanied by a parent or guardian. We are in Texas (snakes, scorpions, poison oak) and most of these places are rocky, so care is advisable. We do collect in some localities where they don't allow anyone under 18, so for out-of-town trips it would be good to check with us before showing up somewhere in north Texas.
Short notice trips are possible, when the Brazos River is low enough to collect, by canoe or kayak.