Take a large bucket and invert, using a 1/4" drill bit, turn it into a strainer leaving almost no bottom, just holes. Switching to the sides use a 1/2" bit and do the same. This will leave you with no weight on the bucket, a good means of allowing debris to fall out [as well as spore] and a solid structure to protect your mushrooms from damage. Do not worry about shrooms falling out because if they fit through the holes you should not have picked them anyway. Add a lid with no holes to prevent foreign matter from falling in, a shoulder strap [at least 1 1/2" wide for shoulder comfort and you are set. If you have a back pack to fit this bucket in you can then carry 2 to 3 of these buckets with you. My pack will hold 2 plus 1 in my hands. This allows me to carry a large volume with no damage to the product whether it be Morel, Chantie, or Pine.  A clean healthy product will guarantee you a better grade which results in more money for the effort.

Just a little tip when making your bucket....after drilling the holes, use a torch around the edge of each whole. This helps add strength, back to the bucket, by preventing cracks from starting from the new holes. In short it will make your bucket last a lot longer. Also try and stay with "white", the dark ones can get a little toasty in the sun.
Joe