All the ranches I lead field trips on have a good quantity of agate on the ground. This occurs because the basalt, where the agate grows, erodes, but the agates don’t, so they’re left in the dirt. Generally, all you need to do is pick them up. The more difficult ones may require you to dig in the soft dirt.
My basic equipment list is this: a table knife, like the ones you can get at a dollar store or thrift store. Stainless steel, all one piece. You use this to dig in the dirt around an agate and pop it out. Next, a chopstick. Use this to clean dirt off of an agate or clean out the inside of a geode so you don’t damage the crystals or mark the agate surface with a metal implement. Third, a toothbrush. This goes with the fourth item, which is a spray bottle filled with water. Use these two together to clean agates to see if they’re what you want. And wetting down an agate helps you see what it will look like polished. Another useful item is flagging tape, which can be used to mark the location where you put your lunch, your bag, or your car, and to mark the location of a rock you want to go back to later.
For putting your finds in, I like the bags we used to get when we went to conferences: canvas, with a couple of fairly long handles so they’ll sit on your shoulder. You can find these at thrift stores, garage sales, and perhaps in your own closet. When the bag gets full and you bring it back to the car, you can empty it into a bucket and start over. That way you don’t have to carry many rocks at a time.
Of course, you want to have a rock pick, a crack hammer or small sledge, and a couple of prybars in your car in case you find the one in a thousand agate that’s still in the basalt. But you don’t need to carry them with you all the time. You can buy some construction flagging tape and take a piece with you as you hunt. Then you can mark where the great rock is that you need to get out of the host rock, and go back to your car for the tools.
Now, I’m spoiled, and I carry something called a gem scoop or treasure scoop. this gadget helps you by allowing you to lift rocks up off the ground without having to bend over. I should have some in my shop to sell by April, or you can get them from Kingsley North at this url: http://www.kingsleynorth.com/skshop/products.php?keys=treasure%20scoop&catID=