Are the beds on the ground & 36 inches deep? Or are they 6-18 deep on legs, like a table? If they are in ground then you need to mix in clay, coco coir or some other organic matter that holds water. If it is on legs, then I would fix a sheet of clear plastic to one side of the bottom, then pull tight across the bottom & fix the other side. But not the ends, so it can drain. This would slow water lose,after a time you can remove it if the bed it too wet or stop watering. You would be treating the bed as a container in both examples. As for covering seeds & seedlings, I am with wayne 5, damp peat moss. Love to see photos!

The ph and complete composition of mushroom compost is going to depend on what the mushroom growers use to make their compost and what they add to it. This will likely vary depending on what type of mushrooms are being grown. The mushroom farm where I get my compost uses gypsum for added calcium so I don't expect that the pH of mine is exceptionally high. The soil the OP has sounds like it is at least on the slightly acidic side (strawberrys mentioned.) And another component of the raised bed mix is peat so I doubt the problems in the raised bed are due to High pH. The manure/Mushroom compost mix may have a fair amount of nitrogen but if it was sterilized before being sold, then it may not have the necessary microbes in it to make the nitrogen available to the plants. Softmentor, your lengthy post about how plants and seeds can't grow in the non mineral soil media, I can't agree with. I have grown plants hydroponically and Therefore know that soil is not necessary. That said, most of my gardening is outside on the ground, the larger deeper rooted plants I'm sure reach the native soil, but a huge number of my plants are actually growing in deep layers of mulch and compost. I've found seedlings sprouting in 4' deep piles of wood chips before so saying that "Seeds can't grow in the "O" horizon, they need to be in the "A" horizon" just doesn't jive with what I have observed in my gardening nor in nature. Some seeds/plants may need the mineral soil more than others but most any plant you can grow in a container with a potting mix can grow without mineral soil provided it gets fertilized with what it needs.

the wood was just old rotting tree stumps. When I put the wood in I covered it up with topsoil and then the sandy soil but before I got the sandy soil put on it rained for days. So basically the ground was saturated through the whole process and I put the garden mix on top before anything dried out. I think it will just take a few weeks to dry that far down to solidify everything. I have planted some flowers since and they are doing ok since the top layer is good. I will post an update soon. thanks for the replies!

Randy... Definitely drill holes in the bottom. You don't want any standing water. A lot of 1/4" holes will do. It looks like you've used regular lumber, which is prone to rapid rot. In a situation like that, I would paint the inside with at least two liberal coats of evaporative cooler coating. You can buy this at hardware stores, Walmart, etc. This is a benign substance, similar to asphalt, and will last for quite a while, protecting the wood from moisture. Do this after drilling the holes, making sure the coating doesn't fill the holes. I would treat the outside with Thompson's Water Seal to further preserve the wood. I would elevate the four posts on bricks or concrete blocks to combat rot. Treat the bottoms of the posts with Thompsons or a copper-based material. Your bed will require 16 cubic feet of artificial soil, which could be expensive, but you only have one small bed. You might first find 10 cubic feet of good peat-based potting soil (five 2-cubic foot bags). mix in five cubic feet of coconut coir (2 bales), and one cubic foot of worm castings. The potting soil will have good water retention, the coir will provide good drainage, and the worm castings will supply the soil organisms. Notice that I didn't mention compost. You shouldn't need it. The mix I described above won't have meaningful amounts of fertilizer, so you can control the nutrients you supply with a water soluble fertilizer such as Jack's 20-20-20, which includes minor nutrients. Have fun.