This is the pocket knife I carry on a daily basis, it's also perfect for harvesting mushrooms.

EDIT: Sorry I didn't see your budget. For under $100 I'd recommend something like the Kershaw Leek. Some Spyderco knives are around your price point too.

Also, if you're willing to get something fixed-blade (non-folding), there are a lot of options there too. Mora knives are hard to beat for the price.