Chard and shard are easily confused words.
The spell-check application of most word processing software programs would not catch a slip-up of these two words. Spell-check is looking for words that aren’t in its dictionary, and words that resemble words in its dictionary, but are possibly spelled wrong. Spell-check isn’t perfect. It doesn’t know and can’t guess what word you wanted, or what word you meant, it can only judge the words on the page. If you used words that are all spelled correctly, it gives you a pass anyway.
Autocorrect suggests words that start with the same letters. It’s suggesting what word you may want to save time, but quite often, its suggestions are pretty off base. They don’t help you out, but they do make you laugh.
Chard (pronounced “shard”) is a noun. It means a plant in the beet family whose green leafy stalks are eaten as a vegetable.
Shard (pronounced “shard”) is a noun. It means a piece of glass or other broken material with sharp, potentially lacerating, edges.
Less common meanings include snail shells, eggs’ shells, scales (like snakes or fish), or the brittle wings covering a beetle’s flight wings.
The following story uses both words correctly:
Sherrilyn was about to buy some swiss chard at the market, when she noticed it was covered in shards of broken glass. A bulb had burst overhead, and a store clerk had yet to clean it up and throw out the affected produce. That was the day she decided she would never shop the bargain market again.