A friend once told me, "It's not worth the effort to pick up any coin on the ground smaller than a quarter."
I've made a hobby of collecting wayward change since I was a child. No amount is too small. It all goes into a fishbowl and at the beginning of each year, I count and roll the coins. Quarters are separated into the "laundry fund" and everything else gets deposited into a savings account. I tend to pick up more pennies than anything else, but they add up.
My fishbowl was only one-third filled when it was time to cash in. I prefer to roll my own coins instead of taking them to an automated sorting machine, like CoinStar. Rolling only takes about 20 minutes and a bank can supply you with rolling papers for free. A CoinStar machine takes 11% of your total as a fee. Don't waste your found money; if your collection of coins grew too large to roll all of them at once, visit the bank periodically to cash in a portion at a time.
So, was my friend right to scoff at picking up anything less than 25 cents? In the past year, I found $16.50 in coins that were not quarters. I'd consider that an amount worth reaching down for.